Hello Robert, Here is the result: This message is received from an email address that is not/was not present in the customer_user: <snip> [otrs@support bin]$ ./PostMasterPOP3.pl Message 1/1 (support@mail.com) Connection to mail.com closed. <snap> so it is OK Here is a message from an email address that has or had (because at one moment I had deleted some of them) an entry in custromer_user. The same thing happens if the email address is for a domain that has an entry in the customer_user, even if the email address is not in the customer_user table. <snip> [otrs@support bin]$ ./PostMasterPOP3.pl Message 1/1 (support@mail.com) Use of uninitialized value in string ne at /data/otrs/Kernel/System/User.pm line 101. Connection to mail.com closed. <snap> which is not OK. I hope I explained everything clear ? Does it make sense for you ? Cheers, Daniel ---- This message has been scanned by BitDefender and found to be clean.