autoreply to email for non-existent users - (resent because I sent the previous one from the wrong email address!)
(Apologies to list maintainers. I'm an idiot. Please delete the earlier mail sent from the wrong address).
Hi Guys
Some advice please.
I own a bunch of domains, not all of which have many (or in some cases, any) real users. One domain name in particular is (accidentally) very similar to a domain in use by a UK QUANGO (one character different). Consequently my domain receives a fair amount of email intended for the other. Naturally I just bounce all email to my domain with a "550 5.1.1 blah@domain: Recipient address rejected: User unknown in virtual mailbox table;"
When I first set up mail on the domain (back in 2011) and started to get lots of mail I did some research and found the QUANGO which should be getting the email. I contacted them and told them about the issue and suggested that they let all their contacts know about the problem. Herein, of course, lies a difficulty. Apart from their regular correspondents, they cannot know in advance who will email them.
I left it, and figured that over time the volume of email would tail off as people caught on. But now, seven years later, I'm /still/ getting mail to my domain which should go elsewhere and which I simply bounce. My logs get cluttered with the bounce message and the end user may or may not know what to do about the failed delivery since I'm just telling them that the user doesn't exist, when they may think he does.
Now to the question.
I'm building a new email server (postfix) and I'm moving some of my doamins to that new server. Since it's a nice clean sparkly new server I'd like to ensure that I don't just move an existing problem from one MTA to another. So I've been pondering whether (and if so how) to implement an autoreply mechanism for my domain which sends a friendly message to the sender saying something like "Hi, you may have a typo in your email address for blah@mydomain. I run that domain and I get a lot of email there which is probably intended for blah@otherdomain. You may like to try resending to the proper address."
I think I could probably set up something using vacation with a catchall alias for any address at my domain. But I'm aware of the potential for a complete balls up if I get this wrong. If "bad people" (TM) find that my mail system will autorespond to any address at a particular domain it could be used as a spamming mechanism which might get my sparkly new MTA blacklisted. I don't want that.
So - any advice on the best approach? Or should I just suck it up as I currently do and not bother trying to be helpful?
Cheers
Mick
--------------------------------------------------------------------- Mick Morgan gpg fingerprint: FC23 3338 F664 5E66 876B 72C0 0A1F E60B 5BAD D312 http://baldric.net/about-trivia ---------------------------------------------------------------------
On 24/01/18 12:17, mick wrote:
(Apologies to list maintainers. I'm an idiot. Please delete the earlier mail sent from the wrong address).
Hi Guys
Some advice please.
I own a bunch of domains, not all of which have many (or in some cases, any) real users. One domain name in particular is (accidentally) very similar to a domain in use by a UK QUANGO (one character different). Consequently my domain receives a fair amount of email intended for the other. Naturally I just bounce all email to my domain with a "550 5.1.1 blah@domain: Recipient address rejected: User unknown in virtual mailbox table;"
When I first set up mail on the domain (back in 2011) and started to get lots of mail I did some research and found the QUANGO which should be getting the email. I contacted them and told them about the issue and suggested that they let all their contacts know about the problem. Herein, of course, lies a difficulty. Apart from their regular correspondents, they cannot know in advance who will email them.
I left it, and figured that over time the volume of email would tail off as people caught on. But now, seven years later, I'm /still/ getting mail to my domain which should go elsewhere and which I simply bounce. My logs get cluttered with the bounce message and the end user may or may not know what to do about the failed delivery since I'm just telling them that the user doesn't exist, when they may think he does.
Now to the question.
I'm building a new email server (postfix) and I'm moving some of my doamins to that new server. Since it's a nice clean sparkly new server I'd like to ensure that I don't just move an existing problem from one MTA to another. So I've been pondering whether (and if so how) to implement an autoreply mechanism for my domain which sends a friendly message to the sender saying something like "Hi, you may have a typo in your email address for blah@mydomain. I run that domain and I get a lot of email there which is probably intended for blah@otherdomain. You may like to try resending to the proper address."
I think I could probably set up something using vacation with a catchall alias for any address at my domain. But I'm aware of the potential for a complete balls up if I get this wrong. If "bad people" (TM) find that my mail system will autorespond to any address at a particular domain it could be used as a spamming mechanism which might get my sparkly new MTA blacklisted. I don't want that.
So - any advice on the best approach? Or should I just suck it up as I currently do and not bother trying to be helpful?
Cheers
Mick
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.
I hope this helps.
Steve
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.
I hope this helps.
Steve
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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
--------------------------------------------------------------------- Mick Morgan gpg fingerprint: FC23 3338 F664 5E66 876B 72C0 0A1F E60B 5BAD D312 http://baldric.net/about-trivia ---------------------------------------------------------------------
On 28/01/18 16:28, mick wrote: [snip]
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.
I missed that the serverfault article was for specific users.
I had another google; this seems more promising, perhaps?
https://www.howtoforge.com/configure-custom-postfix-bounce-messages links to... http://www.postfix.org/bounce.5.html
good luck Steve
On Sun, 28 Jan 2018 18:02:59 +0000 steve-ALUG@hst.me.uk allegedly wrote:
I had another google; this seems more promising, perhaps?
https://www.howtoforge.com/configure-custom-postfix-bounce-messages links to... http://www.postfix.org/bounce.5.html
Thanks Steve.
I had already looked at that. Unfortunately it doesn't do what you might expect it to. Bounces (and the other templates) simply lets you change the error message which will be delivered to /local/ mail users. So I can tailor the message I (or other users of my mail system) get when an email I am trying to send to "blah@domain" fails at some remote system (and I thus get a message like:
"This is the mail system at host smtp.rlogin.net.
I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can delete your own text from the attached returned message.
The mail system
blah@domain: host mailer.for.domain [12.34.67.78] said: 550 5.1.1 blah@domain: Recipient address rejected: User unknown in virtual mailbox table (in reply to RCPT TO command)"
I can change the bounces templates so that the first bit "This is the mail system at smtp.rlogin.net...." and so on says anything I like. But that doesn't help me. I want to do the opposite and change the message I give to other mail systems if I reject a mail.
Thanks anyway. I'm still searching.
Mick
--------------------------------------------------------------------- Mick Morgan gpg fingerprint: FC23 3338 F664 5E66 876B 72C0 0A1F E60B 5BAD D312 http://baldric.net/about-trivia ---------------------------------------------------------------------
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steve-ALUG＠hst.me.uk