How to prevent, or change priority, of dovecot's FAILed relay-submission to relay's IPv6 address, and submit ONLY/first to IPv4?

[Andrew Sullivan]

On Fri, Apr 09, 2021 at 01:15:27PM -0400, PGNet Dev wrote:
>There's no sound reason -- technical or otherwise -- of not providing perfectly legitimate infrastructure-config choices to the admin, and an option to override default behaviors.
>Especially when the override is of defaults that are questionable, internally-made assumptions in the 1st place.
>

There most certainly is a sound reason, which is that it is code that would need to be written and maintained in order to solve a problem that is at least arguably user error.  If the admin specifies a name rather than an IP address, and that name resolves to multiple addresses (whether they be different families of address is irrelevant), then the software is entirely correct in deciding to use any of those addresses in whatever order it wants.  If you want to route around the DNS because of breakage in your local configuration, use a specific address or create a name that contains only the addresses you want. It is unreasonable instead to impose a burden of maintenance on the dovecot developers, or the penalty of poorly-exercised code (since this is, frankly, a corner case) on all the users.

Regards,

A
-- 
Andrew Sullivan
ajs at crankycanuck.ca