I am getting these errors from MailEnable, the OS is CentOS. The errors are from /var/log/maillog as suggested by @OlegNeumyvakin.
Sep 8 03:33:12 localhost journal: plesk sendmail[38416]: handlers_stderr:$
Sep 8 03:33:12 localhost journal: plesk sendmail[38416]: SKIP during call$
Sep 8 03:33:12 localhost postfix/pickup[35664]: 66B7B21F2D4F: uid=0 from=$
Sep 8 03:33:12 localhost postfix/cleanup[38422]: 66B7B21F2D4F: message-id$
Sep 8 03:33:12 localhost postfix/qmgr[9634]: 66B7B21F2D4F: from=<root@loc$
The email cannot send nor receive anything. I am trying to get it to work since it is for a site and it needs to send/receive emails.
You can check your virtual address by command:
postmap -q [email protected] hash:/var/spool/postfix/plesk/virtual
virtual.db is Berkeley DB file
you can check it content with Berkeley DB dump util:
# db5.1_dump -p /var/spool/postfix/plesk/virtual.db
VERSION=3
format=print
type=hash
h_nelem=4103
db_pagesize=4096
HEADER=END
[email protected]\00
[email protected]\00
[email protected]\00
[email protected]\00
[email protected]\00
[email protected]\00
[email protected]\00
[email protected]\00
[email protected]\00
[email protected]\00
[email protected]\00
[email protected]\00
[email protected]\00
[email protected]\00
DATA=END
you can install this util with yum install libdb-utils
Also in case you have issues with sending mail you can check limitations on outgoing email messages at Tools & settings > Mail Server Settings and if you have enabled them Tools & settings > Outgoing Mail Control