Email provider · 5.x.x permanent failure
Every SMTP 552 response on record from Comcast (comcast.net), with the verbatim text, the enhanced status code, a severity rating and a plain-English fix.
The message was rejected for exceeding a size or storage limit, either the recipient's mailbox allowance or a maximum message size set by the receiver.
smtp;552 5.1.1 <example@comcast.net> recipient rejected - extended quota violation
The recipient's mailbox is full or over its storage limit. There is nothing to fix on the sending side; delivery may succeed later once they clear space.
Provider documentation
Postmaster & documentation
The message was rejected for exceeding a size or storage limit, either the recipient's mailbox allowance or a maximum message size set by the receiver. At Comcast, it is a permanent rejection, and the specific reason is in the enhanced status code and message text of each response below.
Match your bounce text to one of the responses below and follow its guidance. Recipient-side wording means fix the address. Authentication or reputation wording (SPF, DKIM, DMARC, blocklist) means fix your sending setup, and check Comcast's postmaster documentation.