smtp dropping emails: what does RSET 250 ... 43 6 mean?

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philip.arny
Posts: 13
Joined: Tue Jul 10, 2018 9:51 pm

smtp dropping emails: what does RSET 250 ... 43 6 mean?

Post by philip.arny » Sat Aug 04, 2018 11:08 pm

Our mail server isn't receiving some emails.

Looking in our logs for incoming SMTP connections:

For those that arrive, the SMTP log shows EHLO, MAIL, RCPT, DATA, and QUIT commands.

For those that don't arrive, the SMTP log shows EHLO, MAIL, RCPT, RSET, QUIT commands.

In the latter case I ?think? the sending mail server is interrupting the transfer with the RSET command:

RSET 250 Requested mail action okay, completed 43 6

Does anyone know what the 43 & 6 codes mean at the end of the line? I've been googling and I get the 3 digit code 250, and I've read about the 3 part SMTP status codes like 4.3.1 (recipient disk full), but neither explains the 43 6 codes.

Any thoughts? Dropping emails seems to happen at random, and I'll trying to diagnose the problem.

Thanks.

Brett Rowbotham
Posts: 543
Joined: Mon Nov 03, 2003 7:48 am
Location: Cape Town

Re: smtp dropping emails: what does RSET 250 ... 43 6 mean?

Post by Brett Rowbotham » Mon Aug 06, 2018 5:07 am

RSET is ReSET and is issued by the sending email server to tell the receiving server to ignore the entirety of the SMTP conversation that had already occurred. In that case, no email would be received. This is a common practice to check if an email address actually exists (via the 250 answer to RCPT).

As for the codes, they are just ME measures for the data length received/sent (as far as I can tell) and of no significance to you.

Cheers,
Brett

philip.arny
Posts: 13
Joined: Tue Jul 10, 2018 9:51 pm

Re: smtp dropping emails: what does RSET 250 ... 43 6 mean?

Post by philip.arny » Mon Aug 06, 2018 2:07 pm

OK, thanks. I did eventually figure out that the RSET commands were, as you say, the result of MailEnable rejecting an incoming email. Spent some time trying to decode those mysterious numbers 43 6!

Philip

MailEnable-Ian
Site Admin
Posts: 9227
Joined: Mon Mar 22, 2004 4:44 am
Location: Melbourne, Victoria, Australia

Re: smtp dropping emails: what does RSET 250 ... 43 6 mean?

Post by MailEnable-Ian » Mon Aug 06, 2018 11:31 pm

Hi,

MailEnable is not rejecting the inbound message. This is your firewall/gateway that is performing a check on the address and then issues the RSET command. There is not data transmitted by the gateway and therefore we never receive the inbound message. We are not rejecting it.
Regards,

Ian Margarone
MailEnable Support

philip.arny
Posts: 13
Joined: Tue Jul 10, 2018 9:51 pm

Re: smtp dropping emails: what does RSET 250 ... 43 6 mean?

Post by philip.arny » Tue Aug 07, 2018 5:50 pm

Huh. We do have a security appliance -- Untangle -- between the MailEnable server and our edge router. Are you saying that Untangle is doing something that causes the sending mail server to send the RSET? That's possible. I'll review both the untangle logs and the MailEnable logs and make sure we're not rejecting mail we actually want to receive. From looking at the from addresses for the incoming messages getting a RSET, it looks like most of them are probably spam (weird, malformed, etc.). So I think this is desired behavior.

I'm spending a lot of time with Logs these days!

Philip

MailEnable-Ian
Site Admin
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Location: Melbourne, Victoria, Australia

Re: smtp dropping emails: what does RSET 250 ... 43 6 mean?

Post by MailEnable-Ian » Wed Aug 08, 2018 12:33 am

Hi,

What I'm saying is,

Messages are coming in via your Untangle spam server/firewall which are then forwarded to the MailEnable server. The SMTP transaction you see in the log snippet where the server issues a RSET command is your Untangle server forwarding the message to MailEnable and checking to see if the email address exists. This is not the remote mail server where the original message derives from.
Regards,

Ian Margarone
MailEnable Support

philip.arny
Posts: 13
Joined: Tue Jul 10, 2018 9:51 pm

Re: smtp dropping emails: what does RSET 250 ... 43 6 mean?

Post by philip.arny » Wed Aug 08, 2018 1:08 am

OK, that makes sense. I didn't realize my Untangle was injecting the RSET. Still curious what the 43 6 (& similar response codes) mean -- are those from MailEnable or someone else in the mail's path?

Philip

MailEnable-Ian
Site Admin
Posts: 9227
Joined: Mon Mar 22, 2004 4:44 am
Location: Melbourne, Victoria, Australia

Re: smtp dropping emails: what does RSET 250 ... 43 6 mean?

Post by MailEnable-Ian » Wed Aug 08, 2018 2:53 am

Hi,

Review this article as it explains what each column represents in the SMTP log file.

http://www.mailenable.com/kb/content/ar ... D=ME020170
Regards,

Ian Margarone
MailEnable Support

philip.arny
Posts: 13
Joined: Tue Jul 10, 2018 9:51 pm

Re: smtp dropping emails: what does RSET 250 ... 43 6 mean?

Post by philip.arny » Wed Aug 08, 2018 6:28 pm

Oh, right -- I did see that page before, and didn't make the connection between the column headers listed there and the columns in the actual log. Thanks!

Philip

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