smtp re-connect delay

Have a Dell Poweredge running SBS2003.
Sometimes, I can connect remotely using telnet on port 25 and ehlo the server.
Other times, I get no answer.

Once connected, everything seems to work well and at a good speed.
If I terminate from the server end, I can't reconnect for about 5 minutes.
If I disconnect from the client end, I can't reconnect for about 5 minutes, and the smtp sessions window continues to show me as logged in (yes... I hit refresh and yes... the seconds increment).

The problem?? We installed a Barracuda Spam Firewall. Works great until it doesn't have any email to forward for awhile. It times out (which is good). But then can't reconnect when it has more mail to forward to the server.
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Jeffrey Kane - TechSoEasyPrincipal ConsultantCommented:

So you're saying that this problem didn't exist before the Barracuda?

Also, how exactly are you watching this SMTP session?  Are you using the SBS"s POP3 Connector for email?

DP-GroupAuthor Commented:
Problem did not exist before Barracuda.
However, I have a hard time blaming them when I can't connect to it directly from a PC.
When email went directly to the server, the email came from many different originators so the reconnect issue never came up. I manage quite a few SBS2003 servers with Barracuda Spam Firewall 200's and I don't have this issue anywhere else.

I am watching the session through exchange system manager.
Go to protocols, smtp, default smtp server, sessions.

Not using POP3 connector. MX record sends mail to barracuda and mail is forwarded to exchange server. I will set the exchange server to only take email from the ip address of the barracuda, but I am waiting on that until I get the smtp reconnect issue resolved.
Jeffrey Kane - TechSoEasyPrincipal ConsultantCommented:

"However, I have a hard time blaming them when I can't connect to it directly from a PC."

Troubleshooting isn't a blame game.  If you really want to know for sure, remove the Barracuda and then see if it resolves.
But that's not really necessary... obviously the Barracuda is causing somthing to barf.... but I think what you're saying is that the fix may not be on the Barracuda.

So, if you have a number of SBS2003 servers with this setup, what's different about this one?  What AV Software is it running?  Is there any other 3rd Party SPAM filtering enabled?  

DP-GroupAuthor Commented:
If I create a connection directly to the IP address of the server, I have effectively removed the Barracuda from the picture. This is where I get the intermittent inability to connect (or should I say abililty to connect as it doesn't work more than it works).

 I  still don't believe it's the Barrracuda per se. I suspect there is a setting or a corruption within exchange/server2003  that keeps SMTP from accepting connecitons from a server that just disconnected.
If I open a telnet session to any other servers, I can connect/disconnect at will. Has anyone seen this behavior anywhere else.
I use Symantec across all servers so no AV S/W issues. No other 3rd party Spam filtering. I'm sure there is a checkmark somewhere that I'm missing, but I'm stumped.

DP-GroupAuthor Commented:
I replaced the linksys Firewall/Router and the problem disappeared.
This makes NO sense as the Linksys worked fine when we didn't run mail thru the Barracuda.
This ends up being a compound problem.

Other servers on the net would continue to try to deliver the email until the Linksys would finally answer, whereas the Barracuda tries / fails and quits trying. I should know better than to use a Linksys in a server environment but that $80 tag gets me every time.

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