Hi, I despretly need help, We are using redhat 5 and using sendmail as our MTA. Recently we observed that when we send a mail with If one unknown internal user is present in addressee , then mail not delivering to valid internal email id and valid external email id as well. mail coming as a single physical file and when sendmail see the user unknown for local domain, mail stopped processing by issuing the following in log User unknown <-- RSET 250 2.0.0 Reset state commands I would be very greatful, If somebody shows the solution for this problem. My manager is on my head for this. Regards, Prakash.