Dear Mr/Mrs/Ms, I have e-mail server using Centos 4.1 So far I can send and receive e-mail using this server, but why to this address: retna at pttropical.co.id can not send? Every time I send e-mail to above address my server always respon with this massage: ----- Transcript of session follows ----- <retna at pttropical.co.id>... Deferred: mail.pttropical.co.id.: No route to host Warning: message still undelivered after 4 hours Will keep trying until message is 5 days old Please help me solve this problem! Previously Thank yuo for your help. Regards, Horasima SML.