@HenryQ
Hey there Henry.
Personally, I think it is a very good idea for all VM email users to either migrate to (1) Google services for their email, or (2) a paid-for email provider such as Proton Mail. I have done both.
I now run the following, all accessed via the Outlook 2019 client:
* 3 x Proton Mail IMAP addresses. Proton Bridge required for this. I have it setup in "Split Email Address mode", so I can get separated emails into distinct and separated folders in the Outlook client.
* 1 x Google IMAP address. Auto-setup on Outlook 2019 available for this.
* 1 x Google POP3 address. App password required for this. This was hard to find inside the Google Account I am using for this. It was quite hidden away among a series of options.
It has been a painstaiking process to set everything up and update all my online accounts. Indeed, I'm only about one-third of the way through updating all my online accounts. I use two password managers (on which I keep identical records), and am working my way through every set of credentials. The two password managers I recommend are 1Password (paid-for, cloud based), and KeePass (free, local machine). If you use these, make sure your "master password" (the one you use to open your password vault) is long, but easy to remember. I like to use a phrase interspersed with numbers instead of spaces. You'd be surpised at how quickly you can type-in a long master password, with practice.
Despite the hassle, I feel that separating myself from VM email provision is worth-it.
I see you noted that there is a possibility that such problems, especially with IMAP setups, could, hypothetically, occur with an alternative provider, such as Google. While, of course, this is possible, the chances are dramatically less. In my opinion, Google are a world-class provider, and their down-time has been negligable over the past 5 years. In my view, the same applies to the paid-for service of Proton Mail, who are another quality provider, with a strong track-record of negligable down-times.
I hope this provides some food for thought for some folks.
One final comment:
If I am no longer "tied in" to VM via their email services, then it will be easier for me to move-on from VM in the future. For instance, CityFibre has just installed cabling/hardware in my street and have mail-dropped all the houses. I am sure I am not alone in this regard.