This document contains an explanation for every question of the Email analysis checklist - the topic that checklist covers, basic explanations and links to tools that may help you to evaluate your email practice.
If you have any questions, feel free to let us know. We will be happy to help you.
Deliverability
Do you have a valid SPF record on the FROM domain?
SPF (Sender Policy Framework) is a basic DNS record that contains data about the trusted servers authorized by your domain so your ISP (internet service provider) can identify a source an email is coming from and detect a forged email. SPF checks that the IP address the email comes from is authorized.
Do you have a valid SPF record on the MFROM domain?
This SPF record covers envelope sending domain that uses SMTP protocol.
How to get your FROM domain:
MFROM domain can be found in the email header.
Find your email in the inbox - > More info - > Show original/header - > look for “smtp.mailfrom” and get the domain from this address (the part after the “@” symbol).
If you use a subdomain, is the main domain protected by SPF?
Using subdomain in email communication is highly recommended for protecting your deliverability and you should have all your domains covered by SPF record.
Blocklist is a set of addresses that are known for breaking the email best practices, fe. sending unwanted messages (spam) or hitting spam traps (explained below).
If you find yourself on blocklist (formerly known as blacklist), you can ask for delisting - contact the blocklist administrator and follow their instructions.
Where to get your sending IP address:
Sending IP address can be found in the email header.
Find your email in the inbox - > More info - > Show original/header - > look for a set of 4 numbers divided with dots like this: 192.157.21.54
Spam traps are email addresses used by Internet Service Providers (ISPs) and blocklist operators to identify senders who aren't following email best practices. These spam trap email addresses may have been legitimate at one time, but are now abandoned or invalid, some were meant to be spam traps from the time of establishing.
Where to get your sending IP address:
Sending IP address can be found in the email header.
Find your email in the inbox - > More info - > Show original/header - > look for a set of 4 numbers divided with dots like this: 192.157.21.54
Do you remove non-existent addresses from your database?
Removing non-existent addresses from your database is essential for keeping your ability to deliver at a high level.
Do you have a valid DKIM signature?
DKIM (DomainKeys Identified Mail) is an email authentication protocol that creates a digital signature that mailbox providers use to verify the identity of an email sender. It is part of antispam and spoofing protection.
Where to get data for your DKIM check:
You need your domain and selector and both can be found in the email header.
Find your email in the inbox - > More info - > Show original/header - > find there “DKIM-Signature” and in this part look for two variables:
Do you have the correct domain for the DKIM signature?
It is essential to have your domain protected, but you have to be sure you are protecting the correct domain.
Where to get data for your DKIM domain check:
Your DKIM domain can be found in the email header.
Find your email in the inbox - > More info - > Show original/header - > find there “DKIM-Signature” and in this part look for variable “d=your.signed.domain.com” - this is your domain
How to check:
Your sending domain should be covered by the domain used at DKIM signature.
Do you have a properly implemented DMARC record?
DMARC (Domain-based Message Authentication, Reporting and Conformance) is a method of authenticating email messages and is based on SPF and DKIM records. It is used for email messages validation to prevent spoofing.
We advise to have DMARC policy (parameter p) set to “reject” or at least ”quarantine”.
Do you have a Feedback-Loop implemented with major ESPs (Email Service Providers)?
A feedback-loop (FBL), sometimes called a complaint feedback loop, is an inter-organizational form of feedback by which a mailbox provider (MP) forwards the complaints originating from their users to the sender's organizations. MPs can receive users' complaints by placing report spam buttons on their webmail pages, or in their email client, or via help desks. The message sender's organization, often an email service provider, has to come to an agreement with each MP from which they want to collect users' complaints.
You have to apply for FBL, so if you don’t have any, contact the ESP you want the Feedback-loop from.
Do you use a third-level domain for sending emails?
Using subdomain in email communication is highly recommended for protecting your deliverability. We recommend consistently separating different types of communication (also because transactional emails have completely different headers).
With Postmaster Tools, you have access to data and diagnostics about your email, including delivery errors, spam reports, and feedback loops. To help email senders meet the requirements in our Email sender guidelines, we've added a new Compliance status dashboard to Postmaster Tools.
Do you encrypt communication using TLS?
Transport Layer Security (TLS) is a widely adopted security protocol designed to facilitate privacy and data security for communications over the Internet. TLS encryption ensures that no third party can read or modify the message.
The most recent version is TLS 1.3, which was published in 2018.
Do you send from the same (sub)domain to which links in the newsletter lead?
Links in your email should lead to the same domain you are using for delivering your emails. This can affect your deliverability, because messages without aligned elements can be considered as spoofing or phishing attacks.
Do you have functional abuse@yourdomain.cz and postmaster@yourdomain.cz email addresses created for each used domain?
Abuse and postmaster accounts are called role accounts. Role accounts are one of the most important internet-standard methods used by mailbox providers, customers, and others to ask questions, report abuse, or send notifications to senders. ISPs (Internet Service Providers) may expect that you have these mailboxes set up and they are needed for Feedback-Loop implementation.
Is your IP address warmed up properly?
This part is one of the important elements that affect your deliverability. You should send emails continually without any big drops or additional batches, because this behavior can be considered as spam attempt.
Where to get your sending IP address:
The sending IP address can be found in the email header.
Find your email in the inbox - > More info - > Show original/header - > look for a set of 4 numbers divided with dots like this: 192.157.21.54
Look at the ADDITIONAL INFORMATION part, EMAIL VOLUME HISTORY bookmark. The graph line there should be flat and without any huge drops or peaks.
Do you have low SPAM scores for the campaigns you send?
There are several words, phrases or even patterns that are often used by spammers and service providers are aware of them. The spam score metrics says how much of these practices are you getting. The lower the score the cleanest your email is.
Is the HTML template properly coded (= not using all-image emails)?
Sending all content in images has a negative impact on deliverability. It’s common spammer practice, so spam filters can block image-only emails. Plus some service providers don’t show pictures at first, so if users want to see any of the content they must allow showing pictures or reach for an online version of email.
Where to check:
Your email - check if your text is embedded in the pictures (not recommended) or if you can see texts out of the pictures (fe. you can select parts of the text with your cursor).
Did the delivered email not end up in the SPAM folder?
There are several “places” in the inbox your message can end up. Main inbox, promotions or spam folder. If you or your ESP are not following the best practices, emails can end in the spam folder. Check this regularly to avoid the worst case scenario - undelivered email.
Where to check:
Reach your inbox and look for your email. If it’s in the spam folder, you should focus on your deliverability issues.
Do you have the correct alignment for all domains used in the newsletter?
Unaligned domains in email can be a trigger for spam check. You should have the same domain through your contact with the receiving party, otherwise your message can be considered as a spoofing or phishing attempt.
BIMI (Brand Indicators for Message Identification) is another identification method that can help the receiver party easily identify you as a sender by displaying the brand's logo next to the email details in the inbox. It helps subscribers to avoid phishing attempts and makes your messages stand out in the inbox.
Where to check:
The easiest way is to check your inbox. For more detailed check you can use online services, fe.:
Are you sending all emails at the time when the customer expects or is used to receiving them?
Delivery time plays a vital role in user engagement. We therefore recommend performing a set of tests and evaluating the optimal time for delivering the newsletter.
We have a busy blog that always runs at the same time and we used to do A/B tests and 8:00 worked best for us, but it's true that it's been a long time.
A lot of tools do have STO (Send Time Optimization) functionality that allows you to send to different recipients at different times based on when they are most likely to engage.
Is it possible to reply to the sending address (= no NOREPLY)?
Your email address should not contain NOREPLY in the username/local part of the address. People should be able to reach you the easiest way - via replying to your message.
Is the sending address reserved for marketing messages?
It is highly recommended to use separate domains for sending corporate, transactional and marketing emails. A bad sender reputation (e.g. due to marking marketing emails as SPAM) can lead to problems with the deliverability of business and transactional emails.
How to check:
Your address for separate communication channels should look like this:
corporate = mymail@mydomain.com
transactional = mail@shop.mydomain.com
marketing = info@news.mydomain.com
Are you using the correct sender name?
Sender name is shown in the inbox as sender as the main identifier for the end user. It should be clear at the first sight who sent the message.
Is the sender name reasonably long?
The inbox window has limited space. Your sender name should be short enough to fit in the sender name box, but still clearly identify you as the sender.
How to check:
The easiest way to check length of sender name, subject and preheader is to open the inbox and look for the email you want to check. The sender nor the subject name shouldn’t be cropped and shown whole. Try several service providers (gmail, yahoo, outlook…) and devices (mobile phone, desktop, laptop, tablet…).
Does the Subject match the content?
The subject of the email should cover the content. Clickbaits or false leads can have a huge negative impact on your open rate statistics in the future.
The subject line is shown next to the sender name in the inbox and has a huge impact on the open rate.
Do you have a sufficiently compelling and specific Subject?
Appropriately and carefully chosen subject line is the key to have your emails opened. It should be grammatically correct and work with emotions (curiosity, pride, excitement, optimism, FOMO…) It is highly recommended to use positive emotions.
Is the Subject reasonably short?
The inbox has limited space for the Subject as well as for the Sender name. The ideal length of the Subject is around 40 characters and should not exceed 10 words. Too long subject lines are cropped so the receiving party can’t see the whole text.
How to check:
The easiest way to check length of sender name, subject and preheader is to open the inbox and look for the email you want to check. The sender nor the subject name shouldn’t be cropped and shown whole. Try several service providers (gmail, yahoo, outlook…) and devices (mobile phone, desktop, laptop, tablet…).
Are you not using emojis in the Subject?
Using emojis can negatively affect your spam score plus may go against receivers preferences. We do not recommend using them in the Subject line.
Are you not using too many exclamation marks / question marks, etc.?
The subject line should be modest and according to the etiquette guidelines. Too many exclamations or question marks can negatively affect your spam score.
Are you not using an all-caps Subject?
The subject line should be modest and according to the etiquette guidelines. All-caps evokes the feeling of shouting we highly recommend to avoid. Using all-caps also can have a negative effect on your spam score.
Are you using a preheader?
The preheader is the text to the right of the subject line that should give a brief preview of the email. If not set properly, preheader text is simply the first text found in an email, mostly the link to the online version of the email or top menu.
Is your preheader sufficiently compelling and specific?
Appropriately and carefully chosen pre-header boosts and complement the subject line. It should be grammatically correct and work with emotions (curiosity, pride, excitement, optimism, FOMO…) It is recommended to use positive emotions.
Is the preheader reasonably short?
The subject line and the preheader have the same column in the inbox and it needs to be reckoned with. Long Subject line gives little space for the preheader.
How to check:
The easiest way to check length of sender name, subject and preheader is to open the inbox and look for the email you want to check. Preheader is visible after the subject of the email. If the combination of subject and preheader is short and fits in the box, it should not be followed by other email content, but the rest of the box should be empty.
Try several service providers (gmail, yahoo, outlook…) and devices (mobile phone, desktop, laptop, tablet…).
Do you have the preheader correctly encoded in HTML?
There should be a string of empty characters after the preheader in the html code, so that only the subject and the preheader are displayed in the email box correctly and are not followed by the message content.
How to check:
Check your HTML code. The top part of the body should contain this code or very similar one:
Your message should contain TXT version (plain text) as well. This version should have the preheader as well.
Design & layout
Is the design visually appealing?
The first impression is really important. Design should be clear and follow your brand color schemes. The reader must be able to tell what the email is about at the first glance.
Are you not using text in images?
The image should be only the image and the text should be only the text. Have all your text in the email in the HTML and not embedded in the pictures. There are a lot of reasons for this practice - visibility of the message if images are not shown, lowering spam score, lower size of the message, easier typo correction…
Do you use consistent visual communication?
Your communication with your recipients or subscribers should be consistent not only in the content way but also in the visual one.
Do you use a width between 600-700 px?
The optimal width for newsletters is generally between 600 and 700 pixels, 500px is the absolute minimum. If your newsletter is too wide, the right side of the content may be cut off and readers will have to scroll horizontally to view all the content. An incorrectly sized email newsletter can hide important information and give you readers bad user experience.
Is the main message visible in the preview pane (max. 300-500px)?
The top of the email should contain the main message you want to tell your subscribers. This part is the first thing they see after opening the message.
Do you have a properly responsive version for mobile devices?
The number of mobile users is increasing every year and a lot of people are reading emails on their mobile phones fe. on their way to or from work. Adjust your template to give them the best experience you can.
Do you have proper ALT texts for images?
Alternative (Alt) Text is meant to convey the “why” or “what” of the image as it relates to the content of an email. It is read aloud to users by screen reader software, and it is shown by email service providers when images are not displayed.
Do you have correct image sizes in HTML?
Pay attention to both the image size and the file size. Both matters:
Width and length: 600px is the most reliable dimension; it works well on screens with 360×640 resolution (which is the most popular screen resolution across both mobile and desktop) and will play well with other resolutions as well. You have quite a free hand with the length of the images since email clients are unlikely to get funky with the length of your images. Just pay attention to how a longer image affects load time.
File size: Because images are downloaded when the recipient opens your email, they don’t affect the total size of your HTML code. What they do affect is load time; anything over 1MB is likely to slow things down, especially for your customers on older mobile networks or slower home internet.
Consider using retina-ready images. Simply create an image twice the resolution at which it will be displayed, and a retina display will use the additional data to show a more detailed image.
Are all images correctly uploaded to the server?
Pay attention to where your pictures are stored. We recommend you to have them uploaded to the server due to the fact that users tend to return to older emails. With images that are not stored properly users can lose some content especially if your main message is embedded into the picture itself and not coded in HTML.
Do you have image resolutions adapted for retina devices?
As said above, we advise using retina-ready images - an image twice the resolution at which it will be displayed so a retina display can use the additional data to show a more detailed and nice looking image.
Call To Action
Do you have a reasonable number of CTAs (Call To Action)?
One newsletter should bear one single message, otherwise the reader can get easily overwhelmed and some information can get lost. So a CTA (button) that's going to encourage clicks should be as focused as possible on a specific action on a specific topic, so the ideal number of CTAs is just one.
We do not recommend having more than three CTAs in the email.
Do you have clickable headlines?
Users often click on headlines, text and images. It's better to have an extra hidden link than lose a potential click.
How to check:
Open your email and try to click on headlines. If there is an embedded link, you should be redirected to the related landing page.
Do you have clickable images?
Users often click on headlines, text and images. It's better to have an extra hidden link than lose a potential click.
How to check:
Open your email and try to click on the image. If there is an embedded link, you should be redirected to the related landing page.
Are the CTAs clearly visible at first glance?
Your CTAs should look like a button - text or some call in defined and confined space, all in contrast colores. CTAs are real buttons only if they look like buttons.
Are the CTAs visible even without loaded images?
Avoid using only-image CTAs. It may be nice looking, but this practice has worse accessibility and most of all, you lose your buttons if images are not displayed.
You can use bulletproof buttons that are nice and work across different service providers.
Are the CTA elements sufficiently large (at least 44 x 44 px)?
The buttons should be large enough in the email. This is both so that it is easy to recognize what the main button is and should entice the reader to click through, but also large enough so that, for example, mobile phone users have no problem hitting the button on the display. Generally, you’ll want to keep CTAs big enough for even large thumbs to easily tap. Apple suggests making touch targets at least 44×44 px large.
How to check:
You have to check the HTML code or you can check it directly in the browser - open the email you want to check, point the mouse on the button, hit the right mouse button and choose inspect. Roll the right bar to the absolute bottom to see the graph like the one below. The size of the CTA + padding should be at least 44 x 44 px.
Do you have valid and working links?
All your links should lead to the existing and relevant page.
How to check:
Go through your email and open every single link. Check if they are valid and the link matches the CTA description or context.
Are you not using "harmful" URL shorteners?
A branded link conveys trust, and impressed short links have a 39% higher click-through rate. But the fact is, using link shorteners in email is an excellent practice for some people like spammers. Using link shorteners grants you a higher spam score and decreases your deliverability.
How to check:
Check your links in the email. For example, a generic Bitly link might look something like:
Do you have the correct measurement codes set up for analytics?
Using UTM codes in your emails can help you better understand what a subscriber does once he/she clicks in your email and visits your website. You'll be able to better track email performance and engagement, including conversions (and assisted conversions), revenue, sessions, page views, etc.
How to check:
Click any CTA in your email and check the landing page address in the browser. The address should look like this:
This UTM parameters combo will tell you exactly how and from where the user got to the page and will help you map his customer journey.
Is the reputation of your trackers good?
Any tool that affects email in some way can affect its deliverability. There are tools that have a good reputation, but there are also tools that are popular with spammers, for example, and just using this tool can do you a lot of harm. This also applies to tracking tools.
How to check:
If you are not sure if your tool has a good reputation, contact us at
Do you have the correct link to the online version of the newsletter?
The web-version of an email is a feature that mailing services offer. It offers recipients the ability to open an HTML version of the email and view it as a web page if it does not display correctly. The web version is often used for sharing the email in social networks.
How to check:
Check your email and look for the "online version" link.
Copywriting & Typography
Do you use the suitable fonts?
Email best practices advice to use email-safe fonts - they are supported by all major email clients including Gmail, Yahoo Mail, and Apple Mail. They’re the typefaces you can be sure will look consistent across all devices, as intended, no matter which email client your subscribers use to read your emails.
You have to check the HTML code or you can check it directly in the browser - open the email you want to check, point the mouse on the text and mark it, hit the right mouse button and choose inspect.
Look for “element.style” or “style attribute” in the right bar. The value of “ font-family” should contain one of the web fonts.
Do you have the correct font size?
All texts should have a font size of at least 14px (ideally 16px).
How to check:
You have to check the HTML code or you can check it directly in the browser - open the email you want to check, point the mouse on the text and mark it, hit the right mouse button and choose inspect.
Look for “element.style” in the right bar. The value of “font-size” should be 14px or more.
Do you have the correct line height?
A classic rule of thumb is to make the line height 1.5 times the size of the body copy. So, a 16-pixel body font multiplied by 1.5 gives us a line height of 24 pixels
How to check:
You have to check the HTML code or you can check it directly in the browser - open the email you want to check, point the mouse on the text and mark it, hit the right mouse button and choose inspect.
Look for “element.style” or “style attribute” in the right bar. The value of “line-height” should be 1.5 times bigger than “font-size”.
Do you have the correct text structure (paragraphs, headings, bullet points, etc.)?
The correct structure of the text is important for clear, quick and clear orientation in the message. It helps in clearly conveying the message you want to convey to your audience. Poorly structured text is confusing, important information can get lost and it looks unprofessional.
Is there adequate contrast between the font and the background?
Color contrast is important because text and background colors can determine how people interact with the content that is written in those colors. Low contrast colors are difficult to read when text contrasts poorly with background colors, while high-contrast colors are easier to read when paired together. A well-chosen contrast also helps with legibility for people with visual impairments.
The standard recommendation for text-to-image ratio in emails is the “60/40 rule,” which means you should be shooting for a minimum of 60% text and a maximum of 40% image. Not only does this help readability, it reduces the chance of being automatically marked as spam.
Do you use suitable copywriting?
Copywriting should be appropriate to the message in the newsletter. It should comprehensively follow the tone of the communication you conduct with your subscribers.
Are there no spelling or grammatical errors in the texts?
Incorrect spelling may happen in random words, proper names, or even in the first and last name of the person you are emailing. Mistakes can hurt the way a customer sees you and negatively affect your image as a professional. Make sure you check spelling every time you send an email.
HTML code
Does the email display correctly in all important email clients?
When testing, be sure to test your email for all major web browsers and mobile devices. You can also use the services of various companies to check, such as emailonacid.com or litmus.com.
The correct and readable display of an email directly affects its readability.
Does the email render properly in the dark mode?
Dark mode is a darker color palette for low-light or nighttime environments. This reversed color scheme uses light-colored typography, UI elements, and icons on dark backgrounds - and it’s one of the hottest digital design trends in recent years and it’s gaining popularity.
Dark mode can change your color scheme, so check if your email is rendered properly even in the dark mode.
How to check:
Set the dark mode on your ESP and check your email. Or contact us at
, we can have your template checked via professional tools like EmailOnAcid.
Do you have the correctly inserted TXT version of the email?
A TXT version or plain text email is the stripped down version of your HTML email. As the word ‘plain’ implies, a plain text email contains only text—no images, stylized fonts, or embedded hyperlinks.
Do you have valid HTML code?
The validity of the HTML code is important for the correct display of the email. Due to the specifics of the HTML used in the email, the code in the validator will contain various syntax and other errors. Despite this, there is a need to keep the code free of unnecessary syntax errors that can negatively affect the rendering of the message in different environments.