My customer have problem with one email account .. he played a bit with whitelist and now his emails are not delivered to another account on same web and domain. He has five email account but problem is with one of them only. I tryed recreate this account but problem still remains. I created new account with different username and set original username as alias but it didn't help. Strange is that sometimes it works ok and another time not. If not I can found line about mail sending in mail.log but no line about delivery.
In which log can I search for some usefull informations? Where is mails which he sent?
Thanks for any sugestions.