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Monday, August 12, 2013, 13:00

Why am I receiving a "521 5.2.1" error from AOL?

Category: General

Solution ID: 00000227


Why am I receiving one of the following error messages: 521 5.2.1 : AOL will not accept delivery of this message; 521 5.2.1 : Service unavailable. Please try again later.


The SMTP reply code 521 indicates an Internet mail host DOES NOT ACCEPT incoming mail. If you are receiving this error it indicates a configuration error on the part of the recipient organization, i.e. inbound e-mail traffic is being routed through a mail server which has been explicitly configured (intentionally or not) to NOT ACCEPT incoming e-mail.

To resolve this issue the recipient organization needs to resolve their infrastructure issues.

In large organizations, with many mail servers, this issue may be a transient error isolated to a particular mail host or cluster configuration (e.g. in a mail server failover situation.) If you are unable to contact the organization to have them resolve your issue, waiting a short time and resending may be all you need to do.


Tags: email, error, aol, service, smtp, infrastructure

See Also:

Link to this article: kb/receiving_521_aol_error

Updated: Monday, August 12, 2013, 13:00

-- David Rutherford


1. Larry Karnis, Friday, January 17, 2014, 18:38:

Karl Timmermans of Microsoft found this article interesting enough to link back to it. See


Last modified: 2013-08-12, 13:00

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