I am troubleshooting an issue where, all of a sudden, we cannot get 100+ recipient emails through our mail scanning service. I checked the track and trace option and see hundreds and hundreds of attempts in excess of the original number of recipients. I opened a ticket with MessageLabs/Symantec and they got back to me with this:
"The problem is that you can not send to more than 100 recipients in a single e-mail. The MessageLabs towers will not allow it. If you attempt to send to more then 100 recipients in a single connection the towers will drop the connection. So your mail server attempts to send the message, but again it will get dropped. This is why you pull up so many results in track and trace.
Therefore to prevent this problem you will have to brake up your list in to 2 or more parts. "
I asked them how to do this but have not heard back. How this works is this: we have our Exchange box set to send all mail to two different DNS names, one primary and one alternate. These take all mail and relay it through the service which scans and delivers. This has not been an issue in the past but I am willing to entertain the support tech and try to do what he is saying.
So is there a way with my configuration to do this? I guess I need to set a recipient limit on the SMTP connector from Exchange to messagelabs but not create issues with sending to many recipients; this needs to be transparent to the user. Is this doable?