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Large Attachment Problem

Printed From: LogSat Software
Category: Spam Filter ISP
Forum Name: Spam Filter ISP Support
Forum Description: General support for Spam Filter ISP
Printed Date: 12 December 2018 at 7:14pm

Topic: Large Attachment Problem
Posted By: kspare
Subject: Large Attachment Problem
Date Posted: 20 August 2010 at 10:55am
I have an odd problem.

I have a customer on a 3mb connection that is having issues receiving large attachments. They have 4 attachments sitting in the queue. The problem is that spamfilter will flood their connection with smtp traffic for days and never complete sending the message.

Right now it's only one user that's having the issue.

What we've found to be happening is, the message attachment is larger than allowed on the exchange server. It rejects the message, but spamfilter tries to send the message again. Creating a loop.

We need this fixed asap!

Posted By: yapadu
Date Posted: 20 August 2010 at 8:00pm
Yes, we have the same problem.  I have reported the issue myself in the past, the ability to set a maximum size email per domain.  The way SMTP works you can't specify a size limit per domain on connection because when a connecting server says helo you tell them the maximum message size you will accept (and you don't know who they are sending for).

BUT, spamfilter could still have a max size established for each domain.  Accept the message and then check the size after accepting it.  That way it can bounce the message and not try over and over to send the message for days until it times out.  It is a massive waste of bandwidth on a message that will never be successfully be delivered.

I added it as a feature request on - this posting back in May.

We have not yet found a work around for this problem ourselves, if you come up with something of a fix outside of spamfilter please post your solution back here.

I am a user of SF, not an employee. Use any advice offered at your own risk.

Posted By: yapadu
Date Posted: 20 August 2010 at 8:04pm
Oh, I just read your posting again.  Your issue is different than ours.  Our issue is that if we accept an email that is 20 megs in size, but the server we are forwarding to only accepts 5 meg attachments then our system will try for three days and never successfully deliver the email.

From what you are describing, it sounds like you suspect there is only enough bandwidth to accept a single message but because 4 messages are being delivered it uses all the bandwidth?

I know by default IIS SMTP will only process an incoming email for 10 minutes.  If the transfer takes longer than 10 minutes it will disconnect, and your server ends up trying again.  You can increase the delivery time on the IIS server if the transfer takes more than 10 minutes to complete.

I am a user of SF, not an employee. Use any advice offered at your own risk.

Posted By: kspare
Date Posted: 20 August 2010 at 8:09pm
Exact same problem. We accept for 40 but they only allow for 20. It resends for ever.

Posted By: LogSat
Date Posted: 21 August 2010 at 8:41am

I emailed you back yesterday asking for a copy of SpamFilter's logfile so we can take a look. In case you did not receive our email (or we did not receive yours with the attachment), I'm leaving you a note here on the forum.

Roberto Franceschetti" rel="nofollow - LogSat Software" rel="nofollow - Spam Filter ISP

Posted By: kspare
Date Posted: 21 August 2010 at 11:06am
Hi Roberto, logs from our side and customer side are on the way.

We've setup a monitor to watch the queue directory size until this gets fixed. 

Posted By: kspare
Date Posted: 22 August 2010 at 12:01am
I did a wireshark trace and found the following:
SMTP    S: 552 4.3.1 Session size exceeds fixed maximum session size

Spamfilter disconnects and retries again later. I guess it just doesn't know how to deal with this problem?

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