On Sun, Jun 07, 2020 at 02:46:53PM +0000, lazuse wrote:
> On Monday, June 1, 2020 6:55 PM, Ondřej Jirman <megatools@megous.com> wrote:
> >
> > MX record is not necessary if the mail server is running on the same server
> > as pointed to by the A record.
> 
> According to RFC 5321, 'the "implicit MX" rule above applies only
> if there are no MX records present.  If MX records are present, but
> none of them are usable, this situation MUST be reported as an error.'
> 
> In the case of megous.com, there exists an MX record vps.xff.cz.
> I am unsure how ProtonMail handled this situation, but my local
> OpenSMTPD reported it as an error and failed to deliver mails.

It really looks fine to me, and the whole setup is almost
the simplest possible:

- my address is megatools@megous.com
- megous.com MX is vps.xff.cz
- vps.xff.cz A points to the address of the mail server

mxtoolbox score is pretty much perfect:

https://mxtoolbox.com/domain/megous.com/?source=findmonitors

Not sure what your OpenSMTPD complained about exactly.

thank you and regards,
	o.