Cannot Send Mail over 10MB in size

Posted on 2010-01-08
Last Modified: 2013-11-30
MS Exchange 2003 Standard SP2
MS Windows Server 2003 Standard  SP2
Barracuda 300 mail Appliance (Smart Host for Exchange)

Just started yesterday.  When I attempt to send mail over 10MB the "remote host drops the connection" according to exchange queue.  The SMTP logs the open and closing of the connection withing 1 second.

Attempted Resolutions:
Restarted Barracuda
Restarted SMTP Services
Verfied message size & Session size restrictions (30MB for size, 100MB for session on Exchange, and 100MB size on Barracuda)
Turned logging all the way up in exchange, no help.
I have removed the Barracuda as the smarthost and the mail does send after that.
Logs on Barracuda supposedly do not show any SMTP connection attempting to send the mail.  Exchange logs show a connect and ehlo, then nothing.

Barracuda says it Exchange (I don't think so).

I am about to try a reboot, if I can't figure anything else out.  The server has been running for almost 4 months without a reboot. (pretty good for a windows box).

Thanks for any help.
Question by:JamesGolden
    LVL 74

    Expert Comment

    by:Glen Knight
    Sounds like a problem with the Barracuda, have you tried changing the setting on the Barracuda just so it gets re-written?
    LVL 76

    Expert Comment

    by:Alan Hardisty
    Have you sent files of this size to the same recipient before without any problems?

    Has something changed at the receiving end?

    Please review my FAQ about problems sending mail to other domains in case something is relevant:
    LVL 21

    Expert Comment


    Well, I think the restriction could be at recipient level and not capable to receive over 10 MB mail.

    Try to send that big mail to some other recipient where you are sure about the limits.

    Faraz H. Khan
    LVL 74

    Expert Comment

    by:Glen Knight
    er......are we missing something......"I have removed the Barracuda as the smarthost and the mail does send after that"

    Just thought I would point this bit out!
    LVL 20

    Expert Comment

    @demazter is right there is problem with Barracuda as the smart hosts just contact the Barracuda.
    Because I have seen many cases.
    LVL 5

    Author Comment

    Thanks for all the help!

    Yea, I can send messages from a cleint (ie Outlook) through the barracuda just fine if it is the SMTP host.

    If I don't use the Barracuda as a smart host (ie. relay), and let exchange connect directly to external hosts all emails will send.

    I can also send files that are 10MB or less to the same recipient, however a 15MB, 20MB and 24MB have failed.

    The smtp connection logs so a connect and ehlo, then nothing.  The connection drops.

    Nothing has changed on the other end, I can send them any email message I want without any attachments.  I have also tried different attachments to make sure that wasnt' the issue.

    I have reset the message size restrictions on the Barracuda (changed them to a larger size, then back).

    Thanks again.  I have set the exchange server to reboot in the middle of the night.  If I don't get it running by then, hopefully that will work.
    LVL 76

    Expert Comment

    by:Alan Hardisty
    Sounds like they have a 10Mb limit set on their inbound email.
    Please telnet to their server and issue the ehlo command and look at the size response:
    telnet 25
    250 CHUNKING
    The above size command shows an unlimited size, your recipient server may be restricted.
    LVL 5

    Author Comment

    I did that and got a 250 - SIZE 100000000 which is 100MB if I count my zeros correctly.

    thanks for the telnet info, I didn't know that before.  Could it be server or domain specific?

    Also when I configured an email client to send mail through the barracuda (without exchange, I allowed my client to relay off the barracuda).  It allowed files of 15mb and 24MB.

    The server didn't reboot correctly last night so I am going to reboot now and see if that solves the problem.
    LVL 74

    Expert Comment

    by:Glen Knight
    Can you check the SMTP connector, under Connectors in Exchange System Manager

    also check the settings if the SMTP Virtual Server
    located under Administrative Groups > First Administrative Group > Servers > Servername > Protocols > SMTP

    check all the locations where size limits can be set:

    also uninstall any antivirus/SPAM software you have on the Exchange server then restart and see if you can send your large attatchments.

    LVL 5

    Accepted Solution

    Thanks demmazter.

    I did already verify all the places where size limits are set.  They were all over 10MB.

    I thought about uninstalling the AV (none for the server specifically, but do have exhcange specific AV.  However a reboot has seemed to resolve the problem.

    I wish I knew what caused this was, but this solution will have to suffice for now.

    Thanks again for all the help
    LVL 76

    Expert Comment

    by:Alan Hardisty
    Ah - the old reboot it fixes it solution!

    Sometimes the simple solutions are the best ;-)

    Expert Comment

    At  'JamesGolden'

    You said "I have removed the Barracuda as the smarthost and the mail does send after that."

    ...Size limit would  not be an issue if set on the exchange because stopping the Baracuda would not affect it.

    ...Kind of tough to check the routing without a tcp dump plus after the reboot it's best (most practical) to assume that wasn't it.

    It does look a bit like a TSO issue with the remote hosts (having an older box and Baracuda in the middle)  since the problem occurred after the DATA section though some errors would be nice too...

    Check the SMTP logs for the test messages with the big files.

    P.S. SMTP aint meant for file transfer no matter what CEO's or VP's think. :)


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