You could use an SMTP transaction filter to reject mail with invalid addresses.

This would not let the mail continue on it's way, but the sender would get an immediate failure, and may become more interested in sanitising their own address list :)

We are currently using Mercury only as an MTA, to send outgoing email.  Some of our users send emails to multiple recipients from email lists that they have.  We track "invalid" email addresses and have a list of known invalid email addresses.  What I would like to be able to do is to scan the recipients of any outgoing emails and remove the known bad email addresses from the email, allowing the email to continue merrily on it's way without the bad email addresses. Unfortunately, the majority of email addresses on these lists are at yahoo.com, and they only allow a certain number of bad email addresses before "deferring" us for 4 hours, making it impossible to send to "valid" email addresses..

 First of all, is this possible, and how would I go about doing it?

 Thanks for any suggestions!

>  First of all, is this possible, and how would I go about doing it?

I would try an scan all of the e-mail lists the users are using to ensure that they are valid before they are used.  THis would be a lot easier if all of these lists were on a server someplace as well. 

Ideally though these people would be using Mercury mailing lists and send their mail to the list rather than using their own e-mail lists.  That way you could easily create a program to clean up the list.  This is especially true if you were using VERP processing of the mailing lists.

Thomas:

 Unfortunately, none of these users work for me, they work for my clients, so I have no control over them..  My clients are all Mystery Shopping companies, and the folks who work for them share lists of mystery shoppers..  We've given them a tool to scrub a list of invalid email addresses, but we can't force them to use it..

At this point, the only control I have is over the mail server, which is why I asked if there was anyway to intercept the emails and "scrub" them..

Thanks!

To get this kind of control over outgoing messages you would need a daemon that can check envelope addresses against the blacklist and remove the matches. A daemon could both kill a message and remove recipients, but it will require some programming to create one.

/Rolf 

Rolf:

Since I am a visual basic programmer, a daemon may be a little beyond my abilities.  I posted on the development forum to see if anyone can help.

Thanks for the info!