draft-martin-managesieve-08.txt [currently expired], section 1.7 says:
Sieve script names may contain any valid UTF-8 characters, except
for NUL, CR or LF. Names MUST be at least one octet long. Zero
octets script name has special meaning (see SETACTIVE command
section). Servers MUST allow names of up to 128 Unicode characters
in length, and MAY allow longer names.
Is this reasonable? I think we should at least prohibit other ASCII
control characters.
Isode's implementation is even more restrictive, as it disallows ¬, :,
/, etc. Should they be allowed?