I'm not ready to drop reddit entirely and to create accounts there I need an email address. I don't want to disclose my phone number or any other personal information.
I tried i2p, but for whatever reason, mail from reddit doesn't get its way to the inbox.
What other providers could I use?
Create your account through old.reddit.com; when it asks you for an email, simply press "next". And, if you need an e-mail provider for some other reason, protonmail.com doesn't ask you for your phone number.
That said do you really need a reddit account?