I do precisely this with Fastmail and it works a treat. Setting up Fastmail with a custom domain was a joy, I can easily filter based on the To address, and you can setup a wildcard identity so you can trivially send email from whatever name you like at your domain.
To me the only downside is the mobile app isn't quite as polished as Gmail. It doesn't work offline, and I notice occasional bugs or awkwardnesses. But it's still very usable, and I much prefer the Fastmail web interface to Gmail.
Edit: Also, the Fastmail importer didn't work very well on my large number of Gmail messages. It failed a few times and restarting it resulted in duplicate messags.
> To me the only downside is the mobile app isn't quite as polished as Gmail. It doesn't work offline, and I notice occasional bugs or awkwardnesses. But it's still very usable, and I much prefer the Fastmail web interface to Gmail.
But FastMail supports other clients, right? I don't want to be forced to use their web interface or their app; I'm happy with the Apple-written Mail apps.
This is the best part of a standards-compliant service like FastMail. Gmail is extremely challenging to use with third party clients because it's custom features aren't supported. I've long had Gmail randomly archive (in no folders) email I told it to delete via an IMAP client, or duplicate items in multiple folders (i.e. labels) or other weird behaviors.
> But FastMail supports other clients, right? I don't want to be forced to use their web interface or their app; I'm happy with the Apple-written Mail apps.
It does, but at least for me the problem is using my separate forwarding-only e-mail address instead of fastmail.com as the sender. As far as I see, I need the native app for this.
FastMail.com can send via a forwarding email address. You'll need to set up authentication at FastMail so it can authenticate to the forwarding service of course.
I don't use the forwarding service to send. I use it to forward incoming mail to FastMail, and in FastMail I just fake the sender address when sending e-mail.
Sadly your use-case is dying. Asymmetric mail flows are becoming harder and harder to support, as DKIM/DMARC alignment and SPF become stronger anti-spam signals, we're going to have to lock down on egress for domains which we don't have proof of control for.
To me the only downside is the mobile app isn't quite as polished as Gmail. It doesn't work offline, and I notice occasional bugs or awkwardnesses. But it's still very usable, and I much prefer the Fastmail web interface to Gmail.
Edit: Also, the Fastmail importer didn't work very well on my large number of Gmail messages. It failed a few times and restarting it resulted in duplicate messags.