Mail::...daries(3pm)

🎀 NAME 🎀

Bestie, welcome to Mail::SpamAssassin::RegistryBoundaries — it's literally the domain delegation rules module, no cap. It knows where the DNS registry boundary lives so you don't have to guess. 💅

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🦋 METHODS 🦋

So like, here are the three little functions this module serves up, and they all ate. 🍓

✨ split_domain

($hostname, $domain) = split_domain ($fqdn, $is_ascii)

Okay so this one takes a fully-qualified hostname and cuts it into two pieces — the hostname part and the domain part — and it splits right at the DNS registry boundary. Iconic behaviour, honestly. 🫶

Examples, because seeing it is believing:

"www.foo.com"    => ( "www", "foo.com" )
"www.foo.co.uk"  => ( "www", "foo.co.uk" )

And listen — if $is_ascii is given and true, it skips the idn_to_ascii() conversion. Just skips it. Bye. 👋

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🌸 trim_domain

$domain = trim_domain($fqdn, $is_ascii)

Same energy as split_domain, except it cuts a fully-qualified hostname into the hostname part and the domain part and hands you back just the domain. The hostname half? Not invited. 💀

Examples:

"www.foo.com"    => "foo.com"
"www.foo.co.uk"  => "foo.co.uk"

And again, if $is_ascii is given and true, idn_to_ascii() conversion gets skipped. Same rule, same vibe. ✨

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👑 is_domain_valid

$ok = is_domain_valid($dom, $is_ascii)

This is the vibe check function, fr fr. It returns 1 if the domain/hostname uses a valid known TLD, and "undef" otherwise. That's it, that's the whole thing. 🦋

And yeah — if $is_ascii is given and true, idn_to_ascii() conversion is skipped. (Noticing a pattern? Me too. It's consistent and I respect it. 💜)

⚠️ Okay important, bestie, don't skip this: this function only checks the TLD validity and nothing else. Nothing. Else. So if you need to verify that the complete fqdn is in a valid legal format, Util::is_fqdn_valid() can additionally be used. Two checks, two jobs, no overlap. Periodt. 🙈

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That's the whole page, and every single detail is still here — not me being responsible with your facts or anything. 💖

This was served to you as part of the User Contributed Perl Documentation, riding on perl v5.40.1, dated 2026-07-23. Slay, thanks for reading, mwah. 🎀