This apparently failed due to the changes made to nsIFileStream.cpp revision 3.29. Backing out the changes fixed the problem. Steps to reproduce the problem: o Using Pop3 account o Start apprunner with -mail o Select a message from a pop3 folder o Copy the message to another pop3 folder via Messages|Copy Message menu item o Select the destination folder o Select newly copied message o Asserts in nsFileTransport

Mark it fixed for dougt and bienvenu. Thanks guys.

Jeff, can you advise me how to verify this bug. We don't see it crash or hang when we use our commercial build.

Just try copy any message from one pop3 folder to anther one. And see if you can open and display the newly copied message. If you can then the problem is fixed.

Win_nt 4.0 (1999-11-22-09 M12) Using the advise from Jeff and the scenario as described in the bug report, I am able to copy a message from POP3 to another folder 1. in the same server 2. in another POP3 server 3. in another IMAP server I can also open and display the newly copied message without any problem.