SMTP command cut-off

Problem reported by Elazar Broad - 9/4/2018 at 7:48 AM

Resolved

Hello -

After upgrading to the 16.x 6816 build, I am running into an issue where the first character of every SMTP command from an iMac client connecting over port 465 (SMTP explicit SSL) is cut off, like so:

10:06:17 [173.xx.x.189][41842435] rsp: 220 xxxx
10:06:17 [173.xx.x.189][41842435] connected at 9/4/2018 10:06:17 AM
10:06:17 [173.xx.x.189][41842435] cmd: EHLO imac
10:06:17 [173.xx.x.189][41842435] rsp: 250-xxxx Hello [173.xx.x.189]250-SIZE 31457280250-AUTH LOGIN CRAM-MD5250-8BITMIME250 OK
10:06:17 [173.xx.x.189][41842435] cmd: UTH CRAM-MD5
10:06:17 [173.xx.x.189][41842435] rsp: 500 command unrecognized
10:06:18 [173.xx.x.189][41842435] cmd: UIT
10:06:18 [173.xx.x.189][41842435] rsp: 500 command unrecognized
10:06:18 [173.xx.x.189][41842435] disconnected at 9/4/2018 10:06:18 AM

This client has worked just fine, until I upgraded to the 6816 build. I've tested manually using OpenSSL's s_client and I can issue commands just fine. Due to PFS ciphers, I cannot capture and decrypt the traffic on the wire to verify that the commands are being transmitted correctly.

Thanks,

Elazar

8 Replies

Reply to Thread

Paul Blank Replied

9/4/2018 at 9:09 AM

This "cut off" looks as if it's part of the problems that others are currently experiencing with IMAP after installing 6816 for both v15 and v16. See other threads.

Elazar Broad Replied

9/4/2018 at 9:44 AM

Indeed, I added a comment to the IMAP thread.

Matt Petty Replied

9/4/2018 at 9:49 AM

Employee Post

Hello,

This is indeed related to the IMAP issue. Infact this will affect POP, SMTP, IMAP, and XMPP. We are coming out and testing a build now that should fix the issue. There was code changed that all 4 of those used and it negatively impacted all of them. Stay tuned for another update.

Matt Petty

Senior Software Developer

SmarterTools Inc.

www.smartertools.com

echoDreamz Replied

9/4/2018 at 11:47 AM

Matt, does the 6821 build the final build that fixes this?

Employee Replied

9/4/2018 at 12:12 PM

Employee Post Marked As Resolution

The new build does address this issue as well. The underlying issue was due to a fix for a potential memory leak with how TCP connections were not being properly disposed.

Matt Petty Replied

9/4/2018 at 12:16 PM

Employee Post

Yes,
Our most recent release 6821 fixes this issue and any other issue relating to odd behavior with XMPP, POP, IMAP, and SMTP (they all use the same TCP processing code). We have a formal response and a technical explanation coming out soon that should explain this issue deeper among other things.

Matt Petty

Senior Software Developer

SmarterTools Inc.

www.smartertools.com

echoDreamz Replied

9/4/2018 at 12:38 PM

That explains the ~17GB of RAM usage that the MailService process was consuming I guess.

echoDreamz Replied

9/4/2018 at 12:40 PM

As always, Thank you Matt!

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