I've had to switch away from CiviSMTP as they've gone under and I'm trying to set up an alternative. SparkPost failed as reported by others as well. I'm now trying to get SendGrid to work. I'm using it in conjunction with the Airmail Extension.
On the SMTP setup page (/civicrm/admin/setting/smtp?reset=1) test emails work fine. But neither CiviMail nor sending email via contact action are working.
With CiviMail it completes the mailing and reports 0 deliveries. All the recipients bounce with "syntax" error.
At SendGrid I've set up the webhook and tested it and it passes the test.
I'm having a vague recollection that I need to allow email headers somewhere but I can't find the setting (if that is even the issue). My client needs to send out a 13K email soon so any help would be much appreciated.
- CiviCRM 5.51.2
- Airmail 2.1
- Drupal 7.91
- php 7.4.3
- Mysql 8.0.30-0ubuntu0.20.04.2