Have you ever dealt with over 1000 bounce-back messages? It's as if every email server on the planet uses a different bounce-back method and message. It's terribly unpredictable. And false positives are the problem I'm talking about.
If you allow bounce-backs or replies with personalized messages, as a larger company, you have to let them through or you will miss something. I don't know support departments big enough to wade through this amount of junk every time you have to notify your user base of something.
What technology can deal with spam, where the originator is actively and maliciously trying to break your filtering algorithm, but is helpless when dealing with bounce-backs, where there is no such intent?
Then you haven't looked very hard. Every CRM system worth its salt (including the free OTRS) supports this. Either by inserting a cookie into the initial mail ("please leave this line intact when you reply") or, smarter, by assigning a dedicated reply-to address to each recipient.
It's not rocket science and adding a "do not reply to this mail" speaks volumes about how little you care about customer service.
And you didn't even mention the Out Of Office automailers in different languages. Or, god forbid, you actually want to send an email with the word "vacation" in the subject -- how can you filter the replies?
99,999% of MTA bounces can be automatically classified, there's not so many different MTA implementations in the wild. The same applies to 99,9% of vacation responders because most people use the standard templates from their Outlook or Webmailer.
The rest is intern-food. A single person can easily classify 20+ mails per minute. And that's what happens in companies with real customer service.
Uh, have you ever actually tried? Because I have, and neither of those numbers are anywhere close to what I experienced. It's probably true that a plurality of the messages are standard Outlook autoresponders, but not "most" -- and definitely not 99.9%. And a very large number of MTAs are either misconfigured or intentional subvert the standard in order to confuse spammers.
These days there are thousands of "So and So doesn't work here any more" messages that have to be removed from the list by hand, then the people using Lotus Notes, Eudora, and god knows what else. Also non-standard Outlook messages and Outlook messages in different languages. Worst is those whitelist anti-spam challenges that require you to fill out a CAPTCHA (or pay the spam filtering company a bribe!) for each message you want to send to a subscriber.
We do comb through the replies because email is an important aspect of our business, but it's a lot more work than you make it out to be. If you're just a small company sending out a monthly newsletter, I'd probably say don't bother.
Have you ever dealt with over 1000 bounce-back messages? It's as if every email server on the planet uses a different bounce-back method and message. It's terribly unpredictable.
Lots of people have done mailshots before. Is there no open-source email-bounce-rejection corpus yet?
If you allow bounce-backs or replies with personalized messages, as a larger company, you have to let them through or you will miss something. I don't know support departments big enough to wade through this amount of junk every time you have to notify your user base of something.