Outlook97 inserts null character

We're using sendmail 8.9.3 The Outlook 97 users are experiencing the following:
When they save a message as a draft twice (it doesn't happen if msg is saved as draft once) prior to sending, Outlook inserts a null-character at the end of the msg causing sendmail to detect an end-of-string, which causes it to not 'retrieve' the very next msg. note: if I vi the mailbox, all msgs are present, and vi reports null char count.

Found MS article that says Outlook creates "draft flag", but no reference to that flag being a null char. Outlook98 and eudora work OK.

Many thanks!

Kim