It's not exactly what you asked for, but an alternative that doesn't require running mail server.
I use gmvault via a docker container. If you want to go a step further you can create a script to run in task scheduler which zip it up daily in a dated file. I can provide mine if you want.
I do this every night.
http://gmvault.org/
Edit: Right, it's pretty abandoned, and you also need this workaround. Bit of a PITA but after the initial setup it pretty much just works and has done so for years.
I'd suggest Gmvault: http://gmvault.org/.
Here's the Docker image I've been running for the last 5 or so years: https://github.com/gaubert/gmvault. Haven't had a single problem.
I've configured mine to run a quick sync twice a week (only downloads mails received since last check) and a full sync once a month (just to be safe).
Also, I do takeouts on all services I care about regularly.
You can use Google Takeout to export everything. If you want to move mail from one account to another, I'd suggest using GMVault. You'll have to import everything (but Mail, if you use GMvault) in each app and you'll lose any sharing or stats.
I feel like most selfhosters have a domain name, so I'd suggest using that for email. I use Google Apps (or whatever they call it nowadays) for email using my own domain.
If Google one day decided to lock me out, I'd just set the MX records to point somewhere else.
Either selfhost it, or I may just create another Gmail account, point my MX records to forwardemail.net and set it to forward all mails to my new Gmail account (in which I would have restored all my emails into using Gmvault).
It really doesn't have to be so scary. It'd be inconvenient, but that's about it.
There's a reason why I just set up my own Nextcloud instance on a cheap rented virtual server in the cloud, and store data on Wasabi. I also have the data stored locally on a NAS, so if either goes kablooey I should be fine. My email is via Google - but using my own domain name, so if the shit really hits the fan there, I can still keep using my email address. The email data itself I back up regularly with http://gmvault.org/ but there are also paid solutions like Spinbackup.
It would certainly still suck hard to get banned off Google but at least if I do I have a plan.
TL;DR: Emails and files in GSuite are deleted a few months after graduation. Your new alum address has none of your undergraduate emails and no ability to use Google Drive.
I see the same thing as /u/gitismatt on my account info page
> You're using 2.31 GB > Google Drive ‒ 0 GB > > Store files up to 5TB each. Anything you create with Docs, Sheets, or Slides won’t use up any of your storage. > Gmail ‒ 2.31 GB > > Attachments sent and received in Gmail as well as your email messages use your storage. > Google Photos ‒ 0 GB > > Per your Google Photos settings, High Quality uploads are stored for free but Original quality uploads will consume your Drive storage.
BUT when I try to navigate to drive.google.com, sheets.google.com, or docs.google.com I encounter the following message:
> We are sorry, but you do not have access to Google Docs. Please contact your Organization Administrator for access.
ALSO your undergraduate emails are not transferred to your new alum address, instead they are unceremoniously deleted. I used gmvault to manually transfer all my emails, but that was kind of a pain.
No good answer for your use case, but I’ll leave that here for others who want to Just backup gmail:
I’ve been using gmvault (http://gmvault.org) for ages now, on various platforms, it’s now running inside a docker on my Synology.
No hassle, and easily portable from system to system.