!! Expected response code 250 but got code "", with message

[peteinlux]

This problem occurs when trying to send a message via an IMAP account configured with SSL/TLS. Problem does not occur when using port 25 with accounts having no encryption enabled. Below is the error message displayed by GO:

Expected response code 250 but got code "", with message ""
Log data:
++ Starting Swift_SmtpTransport
<< 220 MYSERVER.COM ESMTP IdeaSmtpServer v0.70 ready.

>> EHLO int2.MYSERVER.COM

<< 250-MYSERVER.COM Hello 31-178-10-252.isp.com [31.178.10.252], pleased to meet you
250-PIPELINING
250-ENHANCEDSTATUSCODES
250-SIZE
250-8BITMIME
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
250 HELP

>> AUTH LOGIN

<< 334 VXNlcm5hbWU6

>> cHJAdmltZWQucGw=

<< 334 UGFzc3dvcmQ6

>> S29udG9FbWFpbDEyMyE=

<< 235 2.7.0 User pr.myaccount logged in.

++ Swift_SmtpTransport started
>> MAIL FROM:

<< 250 2.1.0 Sender address accepted

>> RCPT TO:

<< 250 2.1.5 Recipient address accepted

>> DATA

<< 354 Go ahead...

>>
.

<<
!! Expected response code 250 but got code "", with message ""

[peteinlux]

Sorry to bother. Turns out our VPN routers were responsible.

[Intermesh]

What was the problem?

[peteinlux]

Same thing here as with PDF issue, VPN and load balancer responsible for corrupted packets. If you anyone experiences anything similar, please try to change the network environment, update your routers firmware