As one user posted, the best way is to do them manually. Proton has a spam filter, but their whole thing is not reading your email.

I have a ton of custom filters myself, so I've got a couple recommendations.

Firstly, just try filtering by sender. If you've got an account on a given forum, shopping site, etc, then make a filter that automatically applies a label for Forums/Shopping/etc based on the email address/domain of the sender. If you know that lemmy is going to send you specifically forum related updates, set it to automatically label any email from your lemmy server as Forum. You get the idea.

If you want to quickly make a filter for a given sender, select the email, hit the Move or Label button, then before clicking Apply, check the "Always move/label sender's emails" box. This creates the rule for you. It just depends on if you want these emails moved to folders, or just tagged with labels.

Secondly, use keywords. So many sites (especially shopping related ones) are gonna be using the same terms very frequently. Think "% off" "black friday" "deal" "sale" "x months free" etc. You can combine all of those into a single filter with the ANY condition set. (This is what I do to delete all the promotional mail from email lists I'm on that are only part promotion, part content.)

I literally never use that and don't understand why anyone would want to. All of the filters I create are created manually (other than spam). When it comes to those, Proton is leaps and bounds better, mostly because Gmail filter creation is just shockingly awful.

It helps that I try to get away from email as much as is humanly possible, in general. Anything that would fall in a "social" category I would expect to get via browser or app notifications, if at all.

Anything "promotional" would never make it into my inbox in the first place. Blogs and similar publications are subscribed to and read via RSS.

If a person asks for my email address I ask them to text me.

I use Proton Mail purely as an act of malicious compliance.