I have strange sender with large number of messages when I show “sender statistic” under Mail log file analysis. Can any one help to understand the meaning of <<>>, <#@[]>.
The problem i found was, that someone was using the server as a relay server. (sending from external adres to a external adres). the meaning <> and #@ can be a virus sending thru your server or spam.
I installed secure mail and disabled the possebility to access the mailserver external by pop or smtp (only secure imap). I installed also the email blocking rpm from dungog. After this the strange mail was gone and my cpu load went from 90% to 3%.