host moved and now 7.01 having problems

I am running a paid for SQL version of 7.01. Forum has been running great until my web host provider moved to a new location. Now when anyone tries to post they get a 500 error. The post is placed on the service and if you hit refresh you get

Your message did not contain a valid subject heading and/or message body.

The new thread or post is viewable, but try to add to it and same things.

You can edit the thread title and there is no problem.

I am sure this is a missing permission someplace, can someone please help me point  my web host techs in the right direction?

Thank You

I would ugrade but I have the other version so modified, it would be a huge pain to rebuild the forum.

The problem was in the Email notification settings. The host installed a new email server, which would not allow the mail.dbsinstall.com setting to work. We had to input the actual IP address.