Protonmail is SuperSecure and all that, but they only have 5GB of storage and for the 4€/month account, getting it close to 30GB would be 6x that. (The quota was much lower when I evaluated the services around 4-5 years ago)
However, the big upside is that I have my own domain now, so if I need to migrate to something else (be it self-hosted or another provider) I can easily do so without losing all my contacts.
When I get bored, I wade through it and either change the address to my current one (with my own domain) or unsubscribe.
For updates, I've got a filter based on substrings in the subject like "receipt", "invoice", "latest bill" which does fairly well at catching that transactional type of email.
It definitely takes more time than Google's implementation, but in curating the filters myself I've found I've been left with a cleaner, more organised inbox.
[0] https://protonmail.com/support/knowledge-base/sieve-advanced...
If you are looking for cloud/managed alternatives you can have a look at the list here https://degoogle.jmoore.dev/
Regarding webmail: MIAB includes Roundcube by default, which is OK on desktop but basically unusable on mobile, so on mobile I just use the built in client that came with my iPhone.
Of course you can use whatever webmail client you prefer, you just install it on a different VPS though (because MIAB will pretty much take over the whole VPS for itself; the only thing you can have alongside it on the same VPS, is a purely static website).
MIAB also includes Nextcloud [ * ] where you can add an alternative webmail client [1]. In order to install that client you need to unlock the nextcloud admin by executing a script that is included in MIAB [2].
[*](in MIAB, Nextcloud is intended to manage calendar+contacts but you can also use it to store files or as an additional webmail client, even though those two use cases are not officially supported by the MIAB devs; this means that, if you have an issue related to storage or webmail, you should seek help from the Nextcloud community, not from the MIAB forums).
[1] https://apps.nextcloud.com/apps/mail
[2] https://github.com/mail-in-a-box/mailinabox/blob/master/tool...