Does DNS 'A' record cover emails too?

Question

In my DNS configuration I've got

Name    Type TTL     Value
gest    A    1800    12.34.56.789

Does it mean that every emails sent to @gest.mydomain.com will be handled by a mail server (if any) on 12.34.56.789 ?

score 2 · Accepted Answer · edited Oct 07 '21 at 07:59

The sending SMTP server will attempt delivery for email messages to @gest.example.com addresses first by looking up the MX record for gest.example.com

In the absence of a MX record for gest.example.com RFC 5321 provides a fallback mechanism:

If an empty list of MXs is returned, the address is treated as if it was associated with an implicit MX RR, with a preference of 0, pointing to that host.

In other words: when your DNS only has the following record:

Name    Type TTL     Value
gest    A    1800    10.34.56.789

SMTP servers should treat that as if the following MX record exists:

Name    Type TTL     Value
gest    MX   0       0 gest.example.com. 
gest    A    1800    10.34.56.789

and route mail accordingly.

So yes, messages to @gest.example.com should be sent to the host with the gest.mydomain.com A record i.e. to 10.34.56.789

Does DNS 'A' record cover emails too?

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