Exchange 2007 Smarthost send connector backing up

Question

I have seen some similar posts to this but none have had any good answers.
We route all outbound mail through an Barracuda spam/virus appliance. We are a busy college campus with roughly 2k staff banging away at our mail gateways with mass mailings to our students, homework assignments, class schedules, blah blah blah..
At no time is our outbound mail queue empty. The trouble is, is that at any given time the most "Active" delivery status messages I see in queue viewer is 6 messages. Whether there are 30 or 5000 messages stuck in there it never try's to send
more than 6 at a time.
Sometimes the queue viewer shows no "Active" connections just all "Ready's". I never see the status change to "Retry" or anything else other than "Ready" or "Active".
We often have delivery delays of 3 or 4 hours when mass mailing messages that do not exceed more than 10 to 20k.
Here is what we've tried so far:
In Powershell use: get-transportserver | fl   (to view these)
and use:  set-transportserver -ConfiguratorName  (to change the values)
updated MaxConcurrentMailboxDeliveries to 50
updated MaxConcurrentMailboxSubmissions to 50
updated PickupDirectoryMaxMessagesPerMinute to 200
MaxConnectionRatePerMinute 1200
MaxOutboundConnections 1000
MaxPerDomainOutboundConnections 1000
"...MaxMessageAttachSize" 100MB (For testing only)
use: get-sendconnector | fl    to verify the value of "MaxMessageSize". Ours is set to unlimited.
use: get-transportconfig   to check all the "Max" settings in there particularly the MaxDumpsterSizePerStorageGroup setting. Ours is 125MB.
Protocol logging is set to Verbose on the send connector. There are no error messages in the send or connectivity logs. The "Microsoft MailFlow Troubleshooter" is a joke.
We have no throttling turned on at the Barracuda level, so says their tech support. I of course have no way of verifying this as I do not have access to it.
I guess my question is. Does anyone know how or where we can increase the number of "Active" messages in the queue to more than 6 messages?

Answer 1

On Thu, 16 May 2013 20:19:55 +0000, Elvis P. Johnson wrote:
>We route all outbound mail through an Barracuda spam/virus appliance. We are a busy college campus with roughly 2k staff banging away at our mail gateways with mass mailings to our students, homework assignments, class schedules, blah blah blah..
>
>
>
>At no time is our outbound mail queue empty. The trouble is, is that at any given time the most "Active" delivery status messages I see in queue viewer is 6 messages. Whether there are 30 or 5000 messages stuck in there it never try's to send more than
6 at a time.
You're sending all mail to a single smart host? I'd be looking at that
machine's configuration.
>Sometimes the queue viewer shows no "Active" connections just all "Ready's". I never see the status change to "Retry" or anything else other than "Ready" or "Active".
You have only one queue, for the smart host, right? Is there a "Last
error" value for it?
Are there any "back-pressure" events in the server's application event
log?
>We often have delivery delays of 3 or 4 hours when mass mailing messages that do not exceed more than 10 to 20k.
[ snip ]
>Protocol logging is set to Verbose on the send connector. There are no error messages in the send or connectivity logs. The "Microsoft MailFlow Troubleshooter" is a joke.
>
>We have no throttling turned on at the Barracuda level, so says their tech support. I of course have no way of verifying this as I do not have access to it.
The barracuda has DOS protection. I *think* the default is to limit
the number of "parrallel connections" to 5, but that may be different
on different models. There are probably other "rate limiting"
settings, too.
>I guess my question is. Does anyone know how or where we can increase the number of "Active" messages in the queue to more than 6 messages?
Rich Matheisen
MCSE+I, Exchange MVP
--- Rich Matheisen MCSE+I, Exchange MVP