[SOLVED] Verify receivers (550) - accepted/bounced ?

[slava_ua]

Hello!

I can't understand why, if recipient verification is enabled (code 550), first a message is sent on behalf of double-bounce and if the recipient does not exist, the response "status = undeliverable" is returned and then the message is discarded - NOQUEUE: reject: RCPT from *: 550 5.1 .1 <*>: Recipient address rejected: undeliverable address -this is correct and should work

But some clients after "status = undeliverable host said: 550 5.1.1 <*>: Recipient address rejected" connect to the mail server and get bounced "status = bounced" and then postfix / bounce [953]: sender non-delivery notification
and Proxmox sends a return letter

I also noticed that if the domain is turned on the White List of the mail proxy, then the client immediately connects to the mail server without checking the recipient

I'm confused !

 

[Stoiko Ivanov]

Please provide the logs for both cases - as I'm not quite sure I understood the issue

Thanks!

 

[slava_ua]

Thanks for the answer!

If you look at the log, then: (More logs in the file)


Oct 8 19:15:54 pmg pmgpolicy [32511]: SPF says pass

recipient verification is turned on and should be like this (NOQUEUE: reject:


(this is an example from another check). (domain name is replaced with *)

Oct 09 13:18:35 pmg postfix / smtpd [21973]: NOQUEUE: reject: RCPT from s1.bomanse.art [176.9.112.42]: 550 5.1.1 <tanechka@*>: Recipient address rejected: undeliverable address: Recipient address lookup failed; from = <emfoftl@holansty.art> to = <tanechka@*> proto = ESMTP helo = <mail.holansty.art>
Oct 09 13:18:35 pmg postfix / cleanup [21976]: DD8C04137F: message-id = <20201009101835.DD8C04137F@pmg>
Oct 09 13:18:35 pmg postfix / qmgr [1031]: DD8C04137F: from = <double-bounce@*>, size = 232, nrcpt = 1 (queue active)
Oct 09 13:18:35 pmg postfix / smtp [21994]: Anonymous TLS connection established to 192.168.0.3 [192.168.0.3]: 25: TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)
Oct 09 13:18:35 pmg postfix / smtp [21994]: DD8C04137F: to = <tanechka@*>, relay = 192.168.0.3 [192.168.0.3]: 25, delay = 0.06, delays = 0 / 0 / 0.06 / 0.01, dsn = 5.1.1, status = undeliverable (host 192.168.0.3 [192.168.0.3] said: 550 5.1.1 <tanechka@*>: Recipient address rejected: * (in reply to RCPT TO command))
Oct 09 13:18:35 pmg postfix / qmgr [1031]: DD8C04137F: removed

and then connecting to the mail server: (More logs in the file)

Oct 8 19:15:59 pmg postfix/smtp[943]: Anonymous TLS connection established to 192.168.0.3[192.168.0.3]:25: TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)



Thanks for the answer!

 

[sametileli]

hello

what's your settings in
please check set
>>>>> mail proxy >>>>>Options >>>>>>Verify receivers >>>>>NO ?

 

[slava_ua]

No, in the settings YES

I also noticed that the recipient check (NOQUEUE: reject: RCPT from) is processed correctly in the based one, but in isolated cases the smtp client connects to the mail server, even if the recipient check was successful
Proxmox mail works for about a month

 

[sametileli]

You are having this problem because that setting is yes.

 

[slava_ua]

Here is a quote from the Postfix instruction:

"Recipient address verification is relatively straightforward and there are no surprises. If a recipient probe fails, then Postfix rejects mail for the recipient address. If a recipient probe succeeds, then Postfix accepts mail for the recipient address"

My problem is that when checking the recipient Postfix should bounce mail, but it turns out that the client still connects to the downstream mail server

 

[Stoiko Ivanov]

My problem is that when checking the recipient Postfix should bounce mail, but it turns out that the client still connects to the downstream mail server

PMG (postfix) will connect to the downstream server sometimes to check if the cached result still is valid - see http://www.postfix.org/ADDRESS_VERIFICATION_README.html#caching
and verify(8)

I hope this explains it.

 

[slava_ua]

Thanks, I also assumed that perhaps this is due to the cache, I will study in more detail on this topic to understand