Postfix

mike-2013 · 02-20-2022, 09:20 AM

I can blacklist an entire domain by adding the line -
gmail.com REJECT You can contact us via our website.

That works and I can see the rejection in the mail logs but the sender doesn't receive the bounce message. If a block a specific user, e.g. -
spammer@gmail.com the sender does receive the bounce message. Is there a way to blacklist the entire domain so the sender does receive the bounce message?

ondoho · 02-21-2022, 03:47 AM

Just a wild thought - maybe sth like

Code:

*@gmail.com

mike-2013 · 02-21-2022, 04:05 AM

Thanks. I had tried that (Great Minds

) but it didn't work. I think the problem is with gmail as a similar block on outlook.com does result in the sender receiving the bounce message.

We receive a lot of spam from these throwaway email addresses. The idea is to bounce messages from these addresses with a message asking genuine users of these services to contact us via a form on our website. Unforunately, if the sender doesn't receive the bounce message, she won't know. We may have to use a different strategy.

ondoho · 02-21-2022, 05:07 AM

I have to admit I answered your post on a whim; I have never used postfix or run my own mailserver.

I made some searches on why the messages don't get delivered, and it appears that there's a lot more options to consider, and the syntax is a proper regex and not a simple glob pattern.

Some random links from a quick search:
https://www.linuxbabe.com/mail-serve...l-spam-postfix
https://blog.tinned-software.net/per...using-postfix/
https://serverfault.com/questions/66...ostfix/1041475
https://serverfault.com/questions/53...ess-in-postfix
https://nacko.net/postfix-block-spec...ntos-6-rhel-6/

Even so, I can't help thinking that blocking ALL gmail addresses because of a few spammers is the wrong approach.

mike-2013 · 02-21-2022, 05:43 AM

Thanks for those links.

We deal mainly with business users who have email addresses on their own domains. We can whitelist the few who use services such as gmail after their initial contact using the website form. It may seem like a heavy handed approach and certainly isn't for everyone.