Postgrey testing

[stefbishop]

Hi,
I was investigating an email that reportedly didn’t get received my system. The same sender did manage to send an email some days later.
It seems the original message was postgreyed, but the sending email server didn’t try again.
The email servers for the 2 emails were different.

My question is. is there a way of probing a foreign mailserver to see if it respects the postgrey protocol?

[openletter]

Postgrey follows RFCs. If a server has been configured to not follow RFCs, you can’t know other than trial and error.

[stefbishop]

The mail log showed this for the first email…

Oct 25 12:28:54 dcwmail postfix/smtpd[15440]: connect from mailomta4-sa.btinternet.com[213.120.69.10]
Oct 25 12:28:54 dcwmail postfix/smtpd[15440]: warning: restriction `reject_authenticated_sender_login_mismatch’ ignored: no SASL support
Oct 25 12:28:54 dcwmail postgrey[15793]: action=greylist, reason=new, client_name=mailomta4-sa.btinternet.com, client_address=213.120.69.10/32, sender=mc.xxxxxxx@btinternet.com, recipient=peter@peterxxxxxxx.com
Oct 25 12:28:54 dcwmail postfix/smtpd[15440]: NOQUEUE: reject: RCPT from mailomta4-sa.btinternet.com[213.120.69.10]: 450 4.2.0 peter@peterxxxxxxx.com: Recipient address rejected: Greylisted, see Postgrey Help; from=mc.xxxxxxx@btinternet.com to=peter@peterxxxxxxx.com proto=ESMTP helo=<sa-prd-fep-046.btinternet.com>
Oct 25 12:28:54 dcwmail postfix/smtpd[15440]: disconnect from mailomta4-sa.btinternet.com[213.120.69.10] ehlo=2 starttls=1 mail=1 rcpt=0/1 rset=1 quit=1 commands=6/7

The successful email came from mailomta8-re.btinternet.com

Thanks
Stef Bishop

[stefbishop]

Thanks. I guess only an appeal to the hostmaster concerned would work. Maybe in their interest to know.

[openletter]

When the mail comes from different mail servers, Postgrey treats each as a new server.

You can use the whitelist feature if this is a regular problem.

I made this guide. It covers one specific scenario and the solution may not perfectly align with your problem, but the general idea of using a whitelist is what I was hoping to communicate:

How to use Postgrey client whitelists

The Postfix Greylisting Policy Server (Postgrey) uses the concept of greylisting to take advantage of mail standards that the vast majority of spammers are not or cannot be configured to support. The postfix process is configured to send incoming mail to postgrey, which determines whether the mail can continue to the next step in the delivery process by checking whether the sender (“client”) or recipient match anything postgrey is configured to match. When the postgrey test fails, postfix will…

Odds are their admins already know about the problem and don’t care to fix it.

[stefbishop]

Thanks.
I’ve put it down to a one off occurence. I will only worry about it if it happens again!
Cheers

[openletter]

Likely it will occur with email from the provider. They have numerous MTAs and don’t bother to configure them to resend using the same server.