[intsunny]

I'm amazed at how email server software is innovating and evolving like never before. We have new implementations of SMTP, IMAP, etc. We even have new protocols like JMAP thanks to the Fastmail guys.

But it also feels like fewer and fewer people are running their own mail servers. Everyone seems to just outsource it to Google or Microsoft. I'm also surprised at how many engineers barely understand how email works. (IE: I have to show them what email headers are and the useful info that can ne found there.)

[keyle]

That's because email delivery is such a weird dance. It's getting harder every year to have your mail delivered without being part of those few services since the protocol is abused so much.

[Nextgrid]

To be fair, you can relay through those services to work around the delivery problem. It's still better than nothing since they now only see your outbound mail, but inbound mail processing & storage is still local & self-hosted.

[t0astbread]

How does that work exactly? Do you set up your server as higher priority MX and the external provider as backup and then configure your server to relay outbound mail through that other service? And all your server has to have is a valid certificate while DKIM/RDNS/SPF get handled by the external service?

Is there anything to watch out for (e.g. w.r.t. bounce mail) in this setup?

Edit: Maybe you don't even have to set up an MX record for the external provider (unless you want to use it as a fallback for incoming mail).

[dugite-code]

That's exactly how it works, although you don't need an external backup modern email servers will retry for many days before returning a undeliverable notification if a valid MX record exists. With email receiving and delivering email are two separate tasks that don't need to be done by the same service.

For example I use Amazons SES. They have SMTP credentials you plug into your server and you add the DKIM and SPF txt entries to your DNS. The only thing that points to your own server is the MX record. Gmail will re-write emails to be FROM gmail while others may allow you to do similar to SES.

You don't actually need a valid cert or IPv6 to receive email, everyone only cares about the sending side of things.

Amazon will want to know what automated systems you have to deal with bounces and complaints to protect their service but that's about it

[t0astbread]

I was thinking of the case where your server has to send out bounce mail but I guess if it's configured right, it should also just relay that.

[dugite-code]

Yup bounce emails are routed just like any other email so they go through the relay. This is actually one of the gotcha's when using fetchmail, you can accidentally send out a lot of unintentional bounce emails from an invalid server if you are not careful.

[patmorgan23]

It's just like doing bulk mail through a third party, except now you're sending your regular mail through them too.

MX records are used to figure out where to deliver mail so you would leave those pointed at your own mail server, no need to set up any MX record pointed to the 3rd party.

You would need DKIM/SPF, etc for sender verification pointed at the 3rd party.

[afavour]

Email is in its own category in this regard, IMO.

I love to throw out a library and implement something myself so I gain a better understanding of what’s going on and maybe even improve on what was there before. But I can’t do that with email. Other servers are going to accept or reject my mail solely based on what my IP is, irrespective of how good my implementation is or is not. I’ve just never found it worth the time to dig into.

[HHC-Hunter]

Quite frankly, it's just not worth the time or maintenance.

[Grimblewald]

You'll eat your words once your only option is corpomail.