Catch email bounce

Question

I will be sending legitimate emails to a list of recipients and some of them are probably obsolete by now.

I wish to know, based on the email bounces, which are obsolete and delete them from the database. Except VERP I haven't seen anything standardized for this task.

Is there some other way that you know about?

Answer 1

There is no other way than VERP. DSN mails are good to extract the precise reason of bouncing, but not all servers send standard DSN mails. In addition to that, DSN mails can be forged which may be an issue. You can add a simple digital signature to a VERP address.

Answer 2

There is absolutely a way to do this. I run the engineering team at Kickbox. Our product takes a list of emails and will tell you which are valid and which are not (without sending to them). We have an API too.

You want to avoid bounces by sending to bad emails. Send to too many and your IP address will be globally blacklisted.

You can technically verify emails yourself through regular SMTP (just stop the SMTP commands before actually sending the email), but there are plenty of weird SMTP edge cases and for any serious number of emails you'll want to do this through a proper email network (like ours :-).

Hope that helps