Think you should definitively move away from your ISP email and to another service. I have used iCloud for several years and even more regularly recently when I started forward domain email to the iCloud mailbox. I haven’t had any filtering issues as referenced above.
iCloud is a solid email provider and it has be ability under the same account to give you additional aliases you can use under that account so you could have a different email address for shopping etc, but it all flows to the same Inbox.
If you go the personal domain route then unlike gmail you cannot set up your domain with iCloud but you can forward messages to iCloud. Most domains offer a forwarding servicing when you buy. I like Hover.com personally.
