Mark Crispin wrote:
On Sun, 23 Feb 2003, Bruce Lilly wrote:
2. It would be more convenient, IMO, to have a uniform limit
for SMTP Path (a.k.a. angle-addr) and for msg-id rather than
two close but different limits.
SMTP addresses and message-ids may use a more or less equivalent syntax,
but I think that it's stretching it to say that they are the same.
I didn't say they are the same (I did say that at one time
the syntax was identical).
If we're going to set a limit, we have to pick a number.
Let me try again, from a different perspective:
1. The NNTP limit appears to be 501 octets, minus whetever the
longest command is, minus one
2. Typical limits for msg-id components and msg-id-like
constructs seem to be a power of two, or one less than
a power of two, e.g.
maximum host name length 255 RFC 1035 [3.1]
maximum subdomain length 63 RFC 1034 [3.5], RFC 1035 [2.3.1], also
RFC 1123 [2.1] for host
maximum domain name length 255 RFC 1034 [3.5], RFC 1035 [2.3.4], RFC
2821 [4.5.3.1]
maximum Path (angle-addr) length 256 RFC 821 [4.5.3], RFC 2821 [4.5.3.1]
The first three are related to the domain part of a msg-id,
and the last has the same general form <local-part(_at_)domain>.
3. So what's so special about 250, rather than 255 or 256?