On 2023/09/09 13:49, Sagar Acharya wrote: > Thanks Peter, your comments were very helpful and I made some progress > > I have currently hosted server at 587. I have also set > > _submission._tcp.humaaraartha.in. SRV > > records which point to 587. However, I think such a thing is not implemented > by default to be detected by mailservers, perhaps, SMTPD. > > Is such a check on other ports in case 25 connection is not established > implemented?
*nobody* does this. There was an opportunity to change how port lookups were done for email when MTA-STS was implemented reasonably recently (it would only help for the small number of senders actually using this, but it would still have been something) - but that just continued to use port 25. If you think about the scope of changes that would be involved across the internet, it's really just not possible to get everyone to change this, so you would still need to list a port 25 receiver at least as a backup MX (and honestly if you can do that, you might as well funnel all mail through that machine). Changes like: - everyone would need software that such a lookup - some firewalls would need changing (it would be reasonable to only permit an MTA to connect to random internet machines on ports needed for email/DNS) I would suggest getting a VPS or hosted server somewhere, and either bave that handle SMTP relay, or have a tunnel to your real mail server so that incoming connections are passed across directly.
