Error sending mail with Civimail

Question

I've switched hosts and the new host's smtp server seems to be rejecting the email I'm trying to send to a group. It can me 2 or 2000 people with the same response. Apparently it does not like the auto generated sender email address? Anyone have that issue and go I d a solution? CiviCRM on WordPress. Both very recent versions.

2017-09-22 16:30:04 [4342] H=(www.sportingdetectiondogs.ca) [184.154.247.100]:33676 I=[184.154.247.116]:25 X=TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128 CV=no SNI="sportingdetectiondogs.ca" F= A=dovecot_login:civicrm@sportingdetectiondogs.ca rejected RCPT : SITEGROUND: b.304.14831.47c90fe51b65dc14@sportingdetectiondogs.ca is not a valid address: Sender verify failed: Sender verify failed 2017-09-22 16:40:04 [48178] H=(www.sportingdetectiondogs.ca) [184.154.247.100]:42556 I=[184.154.247.116]:25 Warning: SITEGROUND: Message from 184.154.247.100. Normal SMTP auth with civicrm@sportingdetectiondogs.ca system user: sporti62 2017-09-22 16:40:04 [48178] H=(www.sportingdetectiondogs.ca) [184.154.247.100]:42556 I=[184.154.247.116]:25 X=TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128 CV=no SNI="sportingdetectiondogs.ca" F= A=dovecot_login:civicrm@sportingdetectiondogs.ca rejected RCPT : SITEGROUND: b.304.14832.46cd2e439db32d78@sportingdetectiondogs.ca is not a valid address: Sender verify failed: Sender verify failed 2017-09-22 18:45:24 [26529] H=(www.sportingdetectiondogs.ca) [77.104.151.189]:51718 I=[77.104.151.189]:465 Warning: SITEGROUND: Message from 77.104.151.189. Normal SMTP auth with civicrm@sportingdetectiondogs.ca system user: sporti62 2017-09-22 18:45:24 [26529] 1dvXdM-0006tt-Ja <= info@sportingdetectiondogs.ca H=(www.sportingdetectiondogs.ca) [77.104.151.189]:51718 I=[77.104.151.189]:465 P=esmtpsa X=TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128 CV=no SNI="usm31.siteground.biz" A=dovecot_login:civicrm@sportingdetectiondogs.ca S=565 M8S=0 T="Test for SMTP settings" from for support@siteground.com support@support.com [~]#

Answer 1

two possible sources of the error:

• you have changed something in the configuration of your mail accounts in civi (or didn't finish the config previously), check the documentation, the "localpart" should not be empty but name of your bounce mailbox (eg if your mailbox is bounce@example.org, it should be "bounce+")

• civimail relies on a trick that most servers implement: if you send and email to bla+whatever@example.org, it will automatically be understood as an alias of bla@example.org

It seems that you need to at least fix the localpart, as your new mail server is more strict and better at catching configuration problems