+----- On Fri, 20 Mar 1998 14:42:54 +0200, era eriksson writes:
[...]
| I'd be even more restrictive. At the very least, I'd exclude
| additional @:s and commas, but since you know what's valid in a host
| name, why allow anything else?
|
| * ^From:.+@([a-z0-9][-a-z0-9_]*\.)*work\.com\>
|
| Caveat: This is not checked against any RFC. (Somebody even told me
| leading numbers are disallowed but I've seen hosts which have them.
| The spamhaus 1stfamily.com comes to mind.)
The DNS RFC doesn't allow leading numerics but requirements for hosts
includes them, you can even have all numerics as there are no all
numeric root domains. Underscore isn't allowed but is common as, to a
lesser degree, is /. Having two or more @'s as well as : and % in an
address is allowed if you are using mail routing.
/Michael