Admins Accuse Microsoft of Hotmail Cap

kurmudgeon writes "The Register is fielding reader tips that Hotmail has placed Draconian limits on the number of Hotmail recipients who can receive an email. The first 10 Hotmail addresses included in a mass email go through just fine, according to these reports. But any additional addresses are returned to sender with a message that reads: "552 Too many recipients." (Microsoft denies it has placed any such restriction on the number of senders.) This would appear to be a violation of RFC 2821, which states: "Rejection of messages (for excessive recipients) with fewer than 100 RCPT commands is a violation of this specification."

Comments

RFC 2821 is not (yet) a standard

[Eric Smith]

This would appear to be a violation of RFC 2821, which states: "Rejection of messages (for excessive recipients) with fewer than 100 RCPT commands is a violation of this specification."

RFC 2821 isn't a standard, though. It's on the standards track, but it has not yet been accepted by the IETF as a standard. The current SMTP standard is RFC 821, also known as STD 10. RFC 821 says:

recipients buffer

The maximum total number of recipients that must be buffered is 100 recipients.

TO THE MAXIMUM EXTENT POSSIBLE, IMPLEMENTATION TECHNIQUES WHICH IMPOSE NO LIMITS ON THE LENGTH OF THESE OBJECTS SHOULD BE USED.

This only requires that up to 100 recipients must be buffered, but doesn't explicitly state that there is any requirement to deliver to all 100 such recipients, nor that recipients cannot be rejected for some reason other than running out of buffer space.