I've been searching and testing for days now without any rational explanation for the following to happen:
I have a mail server which serves all our users and everyone is happily running on IMAP/POP3 access. I need to develop a utility to check POP3 e-mail and started getting errors retrieving mail. I set up the same pop account on my outlook and windows live mail and they couldn't download the e-mails either. I tried another PC and it downloaded just fine. After much debugging and searching, I found out that after sending the RETR command, there wasn't an "+OK" response on my pc but there was on the other pc. So I went down to telnet and sure as day my PC wasn't getting the +OK response on RETR, just the actual mail but I was getting it from every other pc I tried. I even booted up my win XP virtual pc and it has the same result as my pc. Here is an excerpt of the logs from mine and my test pc:
RETR with +OK:
+OK Welcome to MailEnable POP3 Server
USER [email protected]
+OK
PASS <Removed>
+OK
LIST
+OK 3 26743
1 2118
2 23949
3 676
.
UIDL
+OK
1 BE1F75CAE417453581CF11F16CF09989
2 846882DB63B54C9E91C4643AA5CCA1F5
3 A7BAFC28B04A493689A150F6D4CD7FD0
.
RETR 1
+OK 2118 octets
Received: from x ([x.x.60.10]) by x.net with MailEnab
le ESMTP; Sun, 28 Dec 2014 11:30:16 +0200
RETR with +OK missing:
+OK Welcome to MailEnable POP3 Server
USER [email protected]
+OK
PASS <Removed>
+OK
LIST
+OK 3 26743
1 2118
2 23949
3 676
.
UIDL
+OK
1 BE1F75CAE417453581CF11F16CF09989
2 846882DB63B54C9E91C4643AA5CCA1F5
3 A7BAFC28B04A493689A150F6D4CD7FD0
.
RETR 1
Received: from x ([x.x.60.10]) by x.net with MailEnab
le ESMTP; Sun, 28 Dec 2014 11:32:53 +0200
I'm now going to place another hard drive in my pc and install windows and telnet client and see what it does but I was hoping someone might have had some experience with this. It's only that one time that the +OK is missing, every other command has it showing as well as it being there on every other PC I try it on so it's only on my pc that it's missing.
Appreciate any thoughts or assistance!
Well loading a new hard drive worked perfectly as expected which led me to the fact that it must be something installed on my pc itself. Disabled the usual suspects (firewall and AV) and when that didn't work, I proceeded to close down every app running on my pc which possibly works with Ports and eventually narrowed the culprit down to the Fortinet VPN Client running on my PC. I don't have it's AV component enabled so I'm rather at a loss as to how it could be the reason for a single line on port 110 to go missing but if it's running then the +OK line is missing and if it's shut down then it appears.
I'm going to leave this question here in case it can help someone else and will also try post something to Fortinet as well.