Emails from a gmail account are getting blocked/delayed by cox mail server
Ever since mid October 2016, I am having trouble receiving newsletter emails from my child's band group. The newsletter is being sent from a gmail account and I think there are 125+ email addresses in the distribution list. The newsletters are either delayed by a day or not received at all. Prior to October 2016 I had no problem receiving these newsletters.
The sender of the emails gets the CDRBL error code (see full text of the error message below) which the cox site says means:
"The sending IP address has been temporarily blocked by Cox due to exhibiting behavior characteristic of spam"
and that they should:
"The duration of the block may vary depending on reputation and other factors, but will not exceed 24 hours. Inspect message traffic for potential spam, and retry message delivery."
Is there anything that I can do to prevent these emails from getting blocked? Sometimes it is critical that they get the emails to me right away as there may be a last minute change of schedule...
---<text of the received error message>--
Technical details of temporary failure:
The recipient server did not accept our requests to connect. Learn more at https://support.google.com/mail/answer/7720
[mx.east.cox.net. 22.214.171.124: 421 eastrmimpi112.cox.net cox 126.96.36.199 blocked - Error Code: CDRBL - Refer to Error Codes section at http://postmaster.cox.net/confluence/display/postmaster/Error+Codes for more information.
[mx.west.cox.net. 188.8.131.52: 421 fed1rmimpi311.cox.net cox 184.108.40.206 blocked - Error Code: CDRBL - Refer to Error Codes section at http://postmaster.cox.net/confluence/display/postmaster/Error+Codes for more information.