My email not being delivered.

There are a variety of reasons that may cause non-delivery. These can start with your email server being mis-configured,  to your mail server domain or IP address appearing on a black list. The appearance on a blacklist can occur for a variety of reasons.

Over 30% of email marketing messages are not being delivered to recipients. Many of these are blocked because your IP address is on a black list. AOL blocks over 80% of the email that it receives to its members.

Often you are blocked because your IP is in a range of IP addresses that has been marked as sending spam. You may also be blocked because your IP is an open relay.

This means that your email domain may be put on a blacklist and therefore your email may not be delivered without you knowing or having done anything wrong.