After we moved to Exchange 2000, messages being sent using Mail::Sender began to have problems with long recipient lists. If the "TO:" header and the list of recipients exceeds 1024 bytes, the header is corrupted. The message is delivered, but the mime type is ignored. For example, the mime type will be HTML, but the message will be delivered in plain text (tags showing, etc.). The engineer says that the Exchange 2000 server strictly complies to RFC 821, whereas the previous version was more "forgiving". Have you heard of this behavior before, and if so, any ideas on a fix? Thanks.