Still having notification email problems. Keep getting the SendUsing error.

It may be cache related or something. Because if I go to Host Settings and do a test it works and then for a while the notifications work fine. Then at some point after that (usually notice the next day) the notifications don't work again? Is some email value being set by doing the Host settings SMTP test and then cached. If the Forums use that value they work fine until that cached value is cleared.

Is this possible? What else could be making notifications come and go like this?

For the record, I cannot get the forum to send mail either.  I am getting no errors in the error log and the DNN registration emails are going fine.  I have checked my spam filter and my ourbound SMTP logs on the server.  The messages are not showing up in either.  I do have a valid address from address set (have tried several).  I spent some time troubleshooting this, but am hitting a dead end. 

I will be happy to troubleshoot this however I can.  Considering the number of folks that still have not been able to get email working from the forum, this seems like a real issue that should be looked at.  Thanks!

Spence