Once that's done, you can use Mail::DeliveryStatus::BounceParser to parse the bounce message and figure out what addresses to remove.

If you're using an account specifically for sending messages to users in your list, I suggest setting up a .forward file in the home directory of that user and forward the mail to your bounce parser.

It may not work on shared hosting though, and for that you may want to create an email gateway which triggers a perl script. Take a look at Request Tracker's gateway interface as an example. Have your perl script filter the email for bounces, and take action if a bounce is identified, otherwise send the email on it's way.

If you're using exim as your MTA you can set up a system filter to identify bounce messages for you. For example:

if error_message
then
  pipe "/usr/local/bin/handlescript"
  finish
endif
[download]

will pipe all bounce messages to your script and then discard them. That way your perl script only gets called for true bounce messages, which reduces the overhead.

If you want the bounced email to be delivered to the script but also to the original sender, just omit the "finish" keyword.

Then, on the machine that hosts that email address, you need to put in a filter of some sort. Check to see if your server has procmail or maildrop installed. Then write a recipe for that address that processes incoming mail, searching for bounces, and searching in bounces for the original recipient -- this is where perl comes in, as you'll have your filter call a perl routine that will scan the incoming mail. The method for doing so will vary based on the MTA you use, but most have some easily identifiable block within bounced mail showing the original headers, and you can use a regex on those. Then update your database.

Always keep in mind that a message may bounce because (a) a user's account has temporarily exceeded quota, (b) a user's MTA is temporarily down (power failure, maintenance), (c) old DNS for a user's host is cached in the MTA, etc. It's best not to remove a user based on a single bounce. Where I work, we remove a user based on a formula involving consecutive bounces and frequency with which we mail the user. This means that when we update our DB, we're actually incrementing a 'bounced' count. A cronjob then goes through the list later and checks those with high bounce counts to determine if they should be removed.

Good luck!

Thanks everyone. Just one question. How should I formation the prints to sendmail so that the SMTP envelope sender and bounce to addresses are configured correctly? At the moment I'm just using an open command following by some print statements for the TO: FROM:, etc.

Also do you think I could use POP3 to check the bounce email address? That way the script could be contained and run on any hosting account? Or aren't the pop3 modules included in the core?

How can I update the script so that it sees the returned emails, and removes them from the mailing list?

Ask your hosting service if they offer Mailman for managing mailing lists. It takes care of removing dead addresses automatically, which greatly simplifies the management of large mailing lists. Yes, it's written in Python, but so what? It does its job and leaves you free to pursue more interesting things.

Even if your ISP doesn't offer Mailman, they may offer a similar application. Ask them, and find out how they can help you.

I don't think he was asking how to validate an email address.

- dEvNuL