What to do if contacts fail to receive an email?

If you have sent an email campaign, but contacts report they haven't received it, the best practice is to confirm that the email was sent and received.

It's possible one of the following scenarios occurred:

The email was sent to the contact, but the email was blocked by their company firewall or was flagged as spam and forwarded to their spam/Junk folder.
The email address was misspelled or contained illegal characters (e.g. !, #, &) and hard bounced.
The email address soft bounced due to a temporary email server issue.
The email address hard bounced because the account no longer exists.
The email address was suppressed.

Users should check to see if the recipient was suppressed from this email. If so, it may be necessary to remove the contact's email address from a Suppression List.