Feb 18 18:14:23 server1 postfix/master[9905]: daemon started -- version 2.4.5, configuration /etc/postfix Feb 18 18:15:03 server1 postfix/pickup[9908]: 856D0EEF03: uid=33 from=<www-data> Feb 18 18:15:04 server1 postfix/cleanup[9940]: 856D0EEF03: message-id=<[email protected]> Feb 18 18:15:04 server1 postfix/qmgr[9909]: 856D0EEF03: from=<[email protected]>, size=1208, nrcpt=1 (queue active) Feb 18 18:15:12 server1 postfix/smtp[9942]: certificate verification failed for mail.xxx.com: num=18:self signed certificate Feb 18 18:15:12 server1 postfix/smtp[9942]: certificate verification failed for mail.xxx.com: num=10:certificate has expired Feb 18 18:15:12 server1 postfix/smtp[9942]: certificate verification failed for mail.xxx.com:certificate has expired Feb 18 18:15:12 server1 postfix/smtp[9942]: certificate verification failed for mail.xxx.com:certificate has expired Feb 18 18:15:14 server1 postfix/smtp[9942]: 856D0EEF03: to=<[email protected]>, relay=mail.xxx.com[77.79.xx.xxx]:25, delay=11, delays=1.2/0.24/8.8/1.1, dsn=5.1.8, status=bounced (host mail.xxx.com[77.79.xx.xxx] said: 550 5.1.8 sorry, can't find a valid MX for sender domain (chkuser) (in reply to MAIL FROM command)) Feb 18 18:15:14 server1 postfix/cleanup[9940]: 477FCEEF22: message-id=<[email protected]> Feb 18 18:15:14 server1 postfix/qmgr[9909]: 477FCEEF22: from=<>, size=3231, nrcpt=1 (queue active) Feb 18 18:15:14 server1 postfix/bounce[9946]: 856D0EEF03: sender non-delivery notification: 477FCEEF22 Feb 18 18:15:14 server1 postfix/qmgr[9909]: 856D0EEF03: removed Feb 18 18:15:14 server1 postfix/local[9948]: 477FCEEF22: to=<[email protected]>, relay=local, delay=0.29, delays=0.08/0.1/0/0.12, dsn=2.0.0, status=sent (delivered to command: procmail -a "$EXTENSION") Feb 18 18:15:14 server1 postfix/qmgr[9909]: 477FCEEF22: removed how to solve any idea pls?