I havnt seen too many messages about this problem, but I am having it as well.
Here are specifics:
when I use mail app, IF I send the email using the account that I have with the ISP that I am logged on to/though, then I can send email with no problem.
If I try to send the same email using a different email address, then it comes back with an error called a null error.
It does however successfully send a one line email to the intended recipients with the word "quit" in it.
I have thought that maybe my ISP has changed its policy and is no longer allowing email sent through it that has a different return address, but this is not the case, since I CAN send email through this ISP using mac OS9 entourage or outlook express.
Therefore, it is a mail app problem.
I would like to know why it is happening and how I can fix it.
Thnx for any help/comments.