Hello,

A client has a website hosted on Plesk Onyx on our server and in web.config he has setup a connection to the Smartermail server to send orders from his website to their email address and the client's email. He complains that sometimes he receives orders randomly. For example, he receives an order at 9 AM, then the next order from 10 AM is nowhere to be found and then he receives the following order from 11 AM. So one order is missing. I checked the logs and they are pretty vague, I haven't found anything directly related to this on the forum, only articles related to another error that contains the "data transfer failed" string (something with "connection timeout", which we don't have in our error), so I'm not sure what the problem is on our server:

[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] rsp: 220 smartermail-hostname
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] connected at 3/15/2018 10:19:31 AM
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] cmd: EHLO PleskOnyx
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] rsp: 250-smartermail-hostname Hello [PleskOnyxIP]250-SIZE 62914560250-AUTH LOGIN CRAM-MD5250-8BITMIME250 OK
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] cmd: AUTH login b2ZmaWNlQGJpb3NpbXR0ZXJhLnJv
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] Authenticating as sender-email-address
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] rsp: 334 UGFzc3dvcmQ6
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] rsp: 235 Authentication successful
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] Authenticated as sender-email-address
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] cmd: MAIL FROM:<sender-email-address>
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] senderEmail(1): sender-email-address parsed using: <sender-email-address>
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] rsp: 250 OK <sender-email-address> Sender ok
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] cmd: RCPT TO:<recipient-email-address>
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] rsp: 250 OK <recipient-email-address> Recipient ok
[2018.03.15] 10:19:31 [PleskOnyxIP][42721712] cmd: DATA
[2018.03.15] 10:19:36 [PleskOnyxIP][42721712] rsp: 354 Start mail input; end with <CRLF>.<CRLF>
[2018.03.15] 10:19:36 [PleskOnyxIP][42721712] Successfully wrote to the HDR file. (D:\SmarterMail\Spool\SubSpool3\10300251.hdr)
[2018.03.15] 10:19:36 [PleskOnyxIP][42721712] data transfer failed. 
[2018.03.15] 10:19:36 [PleskOnyxIP][42721712] disconnected at 3/15/2018 10:19:36 AM

Can you please help? We don't know what could the explanation for this behaviour be or what to check further. I added the IP of the Plesk server to the Smartermail whitelist, just to be sure.

Thank you