On Fri, 26 Jan 2018 09:44:14 +0000 steve-ALUG@hst.me.uk allegedly wrote:
TOP POSTING, SORRY
When I wrote the below, just a minute or two ago, it sounded helpful. Now I have just re-read it and it sounds all "arse-y" and "do-it-this-way". Sorry. Please read it as me trying to be helpful!!!!
Steve
On 26/01/18 09:37, steve-ALUG@hst.me.uk wrote:
A) I am not an expert B) IANAL (but that's not relevant) C) I have not used Postfix. D) Helpful bit. This might help https://serverfault.com/questions/267446/postfix-custom-reject-message-for-c... E) Rationale:
OK, if you route all "undelivered" emails to a user X, and then X replies to them using an "Out of office", then the "undeliverable" emails are actually delivered, and X replies with a new email. X's emails are all identical, or almost identical, so X is a PRIME candidate for getting marked as a spammer.
[Also, you can get stuck with Out-of-office-ping pong: UserA wrongly emails X@YourDomain X@Yourdomain says "do you mean X@TheirDomain?" UserA emails X@Yourdomain saying "UserA is currently out of the office" X@Yourdomain says "do you mean X@TheirDomain?" UserA emails X@Yourdomain saying "UserA is currently out of the office" Repeat until either you change your auto-reply to be smart, I.e. only reply once, or UserA removes their out-of-office notification.
There is a mechanism for indicating messages can't be delivered. Email should be REJECTED by your email system. That way the sender knows it did not get delivered. In many/most/all cases, the reject message will be displayed to the sender. It appears that you can customise the message (as shown by the hyperlink above), so if you want to be helpful, do that.
Stick with the standard way of rejecting, that's why the standards were agreed. In the event that your domain gets onto a mailing list, REJECTed messages are likely to get you off it. Delivered messages with replies are likely to do nothing.
Re the log clutter. You could investigate to see if reject messages can be logged to a different log file, or not logged (which I don't like), or use something like LogWatch, which monitors and reports on log files, and customise it to suppress or group together the bounce messages, so you can examine at your leisure.
Steve
Many thanks. No, you didn't come across as "arsy", and yes, you were helpful. :-)
Your response actually confirmed that I was right to continue to just give the "correct" 550 error response and not attempt to accept mail to unknown users to the domain in question in any way. The serverfault page you refer to is slightly helpful, but is only applies to individual users@domain, not the whole domain, and in any case I don't /want/ to reject all mail to that domain because I have standard users (postmaster, webmaster, admin, abuse, security etc) for whom I want to accept mail.
So, I will contnue to reject, but I'm still searching for a way to customise the rejection message. If anyone has any ideas, I'd welcome them.
Cheers
Mick
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