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Emails sent to Aol.com via Hosted Email Security getting bounced
03/26/2020 965 11509
Emails sent to Aol.com via Hosted Email Security are bounced with the following bounce-back message:
mailin-04.mx.aol.com (220.127.116.11) #<mailin-04.mx.aol.com (18.104.22.168) #5.0.0 smtp;521 5.2.1 : (CON:B1) https://postmaster.aol.com/error-codes#554conb1> #SMTP#
The issue is due to the sender’s content or volume of messages.
As per AOL's Technical and Policy Requirements for sending Mail to AOL, error code 521 is for Recipient address Rejected.
For more information, please read their policy requirements here: https://postmaster.aol.com/tech-requirements