There also appears to be precedent for such transport limits
finding their way into the message format specification. RFC 822
had no line length limit; the 998 octet limit in 2822 sections
2.1.1, 2.3, and 3.5 appears to be derived from the SMTP transport
limitation.
yes, but that one is completely necessary. if you can't transport
a rfc 2822 message in SMTP then it isn't likely to go very far.
not that it's a bad idea to bound the length of message-ids, but
using this as excuse to say that message-ids are bound by the SMTP
limit on address length is quite a stretch.
Keith