One of the silent killers of deliverability is poor or inadequate bounce handling for non-existent users. By this we mean, when an ISP's mail system tells your mail system "this user no longer exists", "user not found", "no such user", or some variation of that message.
Many of the larger ISPs give your incoming email a rating which is based on, among other things, how many non-existent or no-longer existing email addresses you send to, and how often you keep trying to send to the same address once your system has been told that it doesn't exist. If you send to the same non-existent address more than a couple of times, that's considered poor practice.
The challenge:
Email senders should build bounce handling mechanisms based on code standards. 550 for example, means a non-existing email address. This would be quite simple if the standards always applied. The problem begins when an email sender realizes that ISPs, large and small, do not abide by the standards. For example, a 550 message could actually mean a range of different things from bad address to over-quota in which case you don't want to remove this email from your list. It is also very common for hard bounce messages to be coded 450, 451 and so on. The 450 range is code for soft bounces but in reality ISPs will code anything with any number. To make things even more complicated, bounce messages are received both directly from the MTA (Mail Transport Agent/Authority) or as a reply bounce where you receive a reply mail saying that your email has bounced. Bounce handling mechanisms should be able to handle both types of bounces, analyze them and make decisions – delete the user, retry, hold etc.
To make matters worse for email marketers, ISPs are increasingly deploying the use of grey-lists. This method is a way for ISPs to check that the sending entity is not a spammer by sending a bounce message to a perfectly functioning email that says "please re-send in XX minutes". ISPs using this method may grey list all of your users and expect you to send them again in a few minutes. If you fail to do so your mail will never reach the user.
Handling hard, soft, transient and grey-lists bounces requires real-time bounce management and decision making as well as sophisticated methods to understand the nature of the bounce. Mission impossible? Not quite.
ActiveTrail's Real-time Bounce Manager
ActiveTrail's real-time bounce handling and management system is unique in its ability to understand the precise reason for a bounce and act immediately for its resolution. In simple terms, the technology scans through millions of bounce messages and recognizes patterns which indicate the intention of the message, then routing it to a workflow module that acts immediately for resolution. Unrecognized messages are routed to our ISP relations dept. for analysis and classification. Bounce management is therefore, an ongoing task of understanding new messages, changing and refining old ones and classifying them for routes of action. With this artificial intelligence technology ActiveTrail ensures excellent deliverability and provides you with the best ISP reputation in the market.