[sylware]

spammhaus is blocking self-hosted smtp servers.

Have a look at grey listing.

[inferiorhuman]

With Sonic I have to use their servers for outbound stuff since they block outbound SMTP without a static IP (and they don't offer static IPs with fiber). It's a price I'm willing to pay since I typically don't see false positives (and ye I check my logs periodically) with Spamhaus.

Unfortunately I've moved to Proton and the increase in spam is pretty damn frustrating.

[chmike]

Spamhaus is blocking by IP which can be an smtp server or a client. The SMTP protocol does not allow to distinguish a sending SMTP server from a client.

By using a VPN, you "randomize" the IP address and thus make spamhaus and equivalent services useless. I created my own IP blacklist and tracked it.

The only method I found to filter my spammers is to reject mails from hosts without a name. This eliminated 80% of spam, but it won't last long.

The mail system is completely broken.

[sylware]

use grey listing

[chmike]

I have spammers retrying 20 times before giving up. This protection is well known and easily circumvented be spammers.

[sylware]

but it filters a lot already because many do retry 20 times in less than 20 minutes.