You will almost certainly be able to continue to use forwardemail.net as your SMTP forwarding host for sending traffic. That means that you do either one of tw

You will almost certainly be able to continue to use forwardemail.net as your SMTP forwarding host for sending traffic. That means that you do either one of two things: - keep using forwardemail.net SMTP credentials in all your e-mail clients, such as snappy. Only point those clients to your own server for IMAP4 access (accessing the mailboxes where mail is flowing into your own server). - or else, point SMTP to your own server, and configure your SMTP server to use forwardemail.net as the next host. There are some advantages in that you have your own SMTP endpoint that you can use with multiple devices. In my case, my phone can talk to my own SMTP server for sending mail, and my SMTP server talks to my residential ISP's SMTP server. My phone cannot talk directly to my residential ISP server, because it's not inside their network; it's on an unrelated mobile network. So my SMTP server acts as mail forwarding proxy for the phone. - Sine you keep using forwardemail.net for sending, your reachability is not impacted. Sending SMTP through forwardemail.net is covered in their FAQ. It looks like they have a few configuration hoops to jump through: https://forwardemail.net/en/faq#do-you-support-sending-email-with-smtp https://forwardemail.net/en/faq#do-you-support-sending-email... I'm guessing you know about this because you must be using that with your snappy setup. What catches my eye is that they have some configuration bits where you declare your custom domain. That's not always necessary. For instance, in my setup, my ISP knows nothing about me and my domain. I just connect to their SMTP server, and use whatever From: header I want in my e-mails. The SMTP envelope address is one assigned by the ISP. I also noticed the bit at the bottom of that FAQ about their "manual review process on a per-domain basis for outbound SMTP approval" which supposedly takes 24 hours.