We've updated our CiviCRM to version 5.2.2 and Mosaico to version 2.0 beta 4 and since then we are not able to send any mailing from CiviCRM.
To be clear we can mail to a person individually. Because we are hosting our website on a VPS I was able to check the email log. I noticed that emails (to one person) are going out correctly, but when I try to send a mailing I get something like this "The sender address is not a valid 553 5.1.2 RFC-5321 address.". Sometimes the from address is empty.
I'm hosting on a Plesk server 17.5.2 with PHP 7.1.
Is there someone who has idea's for a solution?
EDIT: Jul 6 11:24:11 srv1 postfix/pickup: B363D8F4B73: uid=10006 from= Jul 6 11:24:11 srv1 postfix/cleanup: B363D8F4B73: message-id=<20180706092411.B363D8F4B73@shost.tld> Jul 6 11:24:11 srv1 postfix/qmgr: B363D8F4B73: from=, size=89808, nrcpt=1 (queue active) Jul 6 11:24:11 srv1 postfix/smtp: B363D8F4B73: to="", relay=aspmx.l.google.com[2a00:1450:4013:c04::1b]:25, delay=0.09, delays=0.01/0/0.07/0.01, dsn=5.1.2, status=bounced (host aspmx.l.google.com[2a00:1450:4013:c04::1b] said: 553-5.1.2 The sender address is not a valid 553 5.1.2 RFC-5321 address. u42-v6si5509030edm.404 - gsmtp (in reply to MAIL FROM command))