SMTP intermittent fail: Can't send message: 354

[ThomasPL10]

Helo all

I'm facing the following issue with my debian/apache hosted OTRS.

For random sent e-mail (roughly 10 per day, with hundrends of e-mail sent every day) the user is prompted with 'Impossible to send message to:...' error. The e-mail itself still appears on the list of articles within the ticket's interface.

In the otrs.log file I can see the following error

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For Exchange SMTP gateway: [Error][Kernel::System::Email::SMTP::Send][173] Can't send message: 354Start mail input; end with <CRLF>.<CRLF>
For Gmail SMTP Gateway: [Error][Kernel::System::Email::SMTP::Send][173] Can't send message: 354 Go ahead w17sm34793wrl.24 - gsmtp

In other thread of the forum I've found that for some user the issue was resolved after he st MaxAcknowledgementDelay to 0 in the Exchange server configuration but for me it didn't fix the issue.
Then I've tried with GMail SMTP gateway instead of the Exchange but the issue was still ther, only the error was slightly different as mentioned above.

I've enabled debug mode for SMTP and I've found that for failed messages it timeouts within SMTP.pm

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Net::SMTP=GLOB(0x7f6465b2cf00)<<< 220 <...> Microsoft ESMTP MAIL Service ready at Tue, 24 Mar 2020 09:53:01 +0100
Net::SMTP=GLOB(0x7f6465b2cf00)>>> EHLO <...>
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 250-SIZE 10485760
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 250-<...> Hello [170.205.210.215]
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 250-PIPELINING
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 250-DSN
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 250-ENHANCEDSTATUSCODES
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 250-STARTTLS
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 250-AUTH
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 250-8BITMIME
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 250-BINARYMIME
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 250 CHUNKING
Net::SMTP=GLOB(0x7f6465b2cf00)>>> MAIL FROM:<...>
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 250 2.1.0 Sender OK
Net::SMTP=GLOB(0x7f6465b2cf00)>>> RCPT TO:<...>
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 250 2.1.5 Recipient OK
Net::SMTP=GLOB(0x7f6465b2cf00)>>> DATA
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 354 Start mail input; end with <CRLF>.<CRLF>
Net::SMTP=GLOB(0x7f6465b2cf00)>>> MIME-Version: 1.0
Net::SMTP=GLOB(0x7f6465b2cf00)>>> Subject: <...>

<...>

Net::SMTP=GLOB(0x7f6465b2cf00)>>> ------------=_1585039980-13994-2--
Net::SMTP=GLOB(0x7f6465b2cf00)>>> .
[Tue Mar 24 09:53:30 2020] -e: Net::SMTP=GLOB(0x7f6465b2cf00): Timeout at /opt/otrs//Kernel/System/Email/SMTP.pm line 171

Net::SMTP=GLOB(0x7f6465b2cf00)>>> QUIT
Net::SMTP=GLOB(0x7f6465b2cf00)<<< 250 2.6.0 <...@...> [InternalId=11064118] Queued mail for delivery

The server load is OK. the 'top' command shows counter between 0.1-0.4. Everything below 1 means that the server is capable of the load.

I'd appreciate if you can point me at any direction with that issue as I'm just out of ideas for this one.

[skullz]

i point you here..not sure gonna help or not.,mostly exchange issue ?

viewtopic.php?t=13414

[ThomasPL10]

Yeah I've already spot this article earlier. I've tried with that setting but still I was able to repro the issue. I've also tried with GMAIL SMTP Gateway to take the Exchange out of the picture but still the issue pops out from time to time during the day.