Considering Self-Hosting Email with Proxmox Mail Gateway: Advice Needed

[ensnare]

I've been contemplating a move back to self-hosting my email services, and I'm considering a setup where I host the mailbox and mail services at home, complemented by a Proxmox mail gateway in the cloud. The idea is to configure the at-home mail server to relay both incoming and outgoing emails to the cloud-based Proxmox mail gateway.

Has anyone implemented a similar setup before? If so, I'd greatly appreciate any insights or advice you might have. Additionally, are there any important factors I should keep in mind when setting up this configuration?

One potential advantage I see with this setup is that in the event of my at-home server going down, emails would still be received by the cloud mail gateway and then relayed to the home server once it's back online. Can anyone confirm if my understanding is correct? Furthermore, if this is indeed the case, I'm curious about how long emails would be "stored" on the cloud server before being forwarded to the home server upon restoration of connectivity.

Also, is this a secure setup? How would something like this compare to Proton Mail, for example.

Thanks!

 

[keeka]

One potential advantage I see with this setup is that in the event of my at-home server going down, emails would still be received by the cloud mail gateway and then relayed to the home server once it's back online. Can anyone confirm if my understanding is correct? Furthermore, if this is indeed the case, I'm curious about how long emails would be "stored" on the cloud server before being forwarded to the home server upon restoration of connectivity.

Firstly I haven't done this myself but AIUI postfix re-attempts delivery at specified intervals (default every 4 hours and gives up after 24 hours). This is configurable, directly in postfix if not by PMG. The PMG web UI has a deferred mail report which gives you a view of queued mail.
As to how to trigger a mail delivery, when your mail server comes back online (rather than wait for the next attempt), not sure how you'd do that. I imagine it's not too difficult.
EDIT I got that wrong.
re 24 hours - it may by default actually be considerably longer. https://www.postfix.org/TUNING_README.html#hammer
AND 4 hours is the default warning time rather than re-attempt delivery interval!