I need a custom domain (or three). And I have a family of 6 people.
So that's $5 / user / month = $30 / month = $360 / year.
Unfortunately, that's not justifiable for me. And thus why I'm stuck using Gmail with a custom domain.
Recently compared Google, Office 365, Proton, Tutanota, Skiff, and Zoho. Surprisingly ended up with Zoho. Actually a decent experience so far, they've definitely upgraded their stack for the better from what I remember it was a decade ago.
You pay for mailbox size and number of emails in/out. Can add as many domains/users as you like.
I use the micro tier ($20 a year), it's more than enough for me.
Google Workspaces is $6 / user / month.
I presume you were grandfathered for free from personal G Suite, but for the rest of us fastmail is actually less expensive than google's offering (though google also gives you Drive space and whatnot).
Only one of your accounts needs to be Standard tier ($50/y) to allow up to 100 custom domains. The other 5 accounts can be Basic tier ($30/y) and still use as many custom domains as you give them access to. Total undiscounted cost for your family would be $200/y.
Use the 25% 1Password discount to reduce your total to $150/y. You have the option to extend that 25% discount up to 3yrs and receive an additional discount for paying in advance. Your total for your first 3 years would be $420, then $560 for each 3 years thereafter.
Alternatively, you could consider allowing all your family members use the same Standard account ($105 for the first 3yrs) but with multiple email addresses. Use labels to surface each address for the relevant family member.
In my case, I created a family@surname address for any family business, and a name@surname address for each family member. Each family member has set their Fastmail app to focus on their own address. Yes, technically, they can see each other's email, but it hasn't been a problem. I presume they use throwaway gmail accounts for stuff they want to keep totally private.
We share a specific custom domain for our masked emails and love that feature, especially the 1Password integration although that has some rough edges.
It's not suitable for bulk sending, but for transactional and personal email, I've found it meets my needs.
Be warned, however, that it appears to be a one-man band, and if he goes under a bus...
I'm also a happy user of Migadu. More polished GUI and more features. I've never hit their limits, so not sure how suitable it would be for a medium-sized enterprise. As with Purelymail, it's not intended to be used as a bulk sending service.
Then I realized the alternatives (including letting everyone in the family decide their own email solution) were worse.
I've been using this for a year or so and my family's been happy with it.
So I guess this is tied up then.
The custom email domain is a side feature... but it does work well, and it's essentially free (assuming you want your photos properly backed up... and who doesn't).
I'm not sure if that help article is accurate though - I would think you can subscribe to iCloud+ from their website. You have to go to the website to manage your email domains for example.
I don't think you'd need any Apple gear at all to use it, but make no promises.
But honestly, I think even if I didn't expense - I'd still pay for it. It's a great product; everything is top-notch.