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SMTP 521 and 556 Reply Codes
RFC 7504
Status
Email expansions
History
Recipient expansions
Mail trigger
To
Cc
doc_added_comment
rfc7504@ietf.org
doc_external_resource_change_requested
barryleiba@gmail.com
doc_state_edited
barryleiba@gmail.com
,
rfc7504@ietf.org
ipr_posted_on_doc
rfc7504@ietf.org
ipr-announce@ietf.org