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Subject: Re: [PHP-DEV] Pre-RFC discussion about adding a DNS function for Null
 MX handling
Date: Wed, 13 May 2026 11:48:28 +0200
References: <CALLMduBAgnJe45s3jEwH_qEBGj6WQOBymHzvx3QMc6iaEazxvw@mail.gmail.com>
To: internals@lists.php.net
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Message-ID: <9957BCCA-10E7-45BD-ABA8-B504DD14F60E@cschneid.com>
From: cschneid@cschneid.com (Christian Schneider)

Am 13.05.2026 um 03:47 schrieb Samuel Fontebasso <samuel.txd@gmail.com>:
> I would like to gather feedback before drafting an RFC for a small =
addition to PHP's DNS functions:
>=20
>     dns_check_mx(string $hostname): bool
>=20
> The function would check whether a hostname has at least one non-null =
MX record.
>=20
> Proposed behavior:
> - false when there are no MX records;
> - false when all MX records are Null MX records;
> - true when at least one MX record has an exchange target other than =
".".

Am I correct that this would be equivalent to the following (example.com =
<http://example.com/> return empty string "" for MX, not a dot ".")?
	array_any(
		dns_get_record($hostname, DNS_MX),
		fn($r) =3D> $r["target"]
	)

I'm torn between providing in-core helper functions for common problems =
(and getmxrr/dns_get_mx is indeed misleading/annoying with its bool =
return value) but on the other hand I'm not sure checking for an MX is =
something usually done by the general developer. This sounds more like =
part of a library/framework as there are further complications when =
trying to determine about the ability to send email to an address.

Because of this I'd probably not add another helper function and try to =
handle it on the documentation level instead.

Regards,
- Chris