To receive here the emails of a non-Gmail account, we actually use a Gmail address which is configured to access that non-Gmail account. Then the dedicated Gmail pack is used to funnel these emails in Coda.
To have the same setup:
login to a Gmail account, select “Accounts and Imports” and in the section “Check email from other accounts:”, select “Add an email account”. Then fill in the information required for your non-Gmail account.