I know, your web server will get blacklisted too.
No they won't. You're talking out of your arse. Email is a general concern for self-hosting applications. For many other cases there's no real large scale program to block something. Sure a few shitty US based ISPs still act like it's the late 90s and don't want you hosting a server, but in most of the world that is simply not an issue.
Web servers especially are blocked at worst on an end user basis. While I have no ability to host an email server, and my IP is actively on a blacklist for email all other things I've self hosted weren't even blocked by China, let alone anyone else. Mastodon instances are blocked by specific peers, not by a network on the whole.
As for AV software. Frankly if anyone runs software that stupid they deserve the error messages they get.
You could maybe run your own cloud stuff, but I'd advise against it unless you really know what you are doing and are willing to put the time into keeping it secure.
Doing so is actually quite trivial, as is keeping it up to date. You may think that nerds are a dying breed, but they really aren't. Firing up Ubuntu Linux (which automatically self applies security updates), following an idiots guide to Nginx, installing Seafile using the recommended guide on the website, and applying security updates when you get an email of an updated release is trivial, and boom you've self hosted secure cloud storage. For good measure fire up fail2ban to stop the brute forcing.
I'd suggest putting it all behind a VPN instead
So ... literally what this service is we're talking about? Glad you're finally on board.