I run a marketplace website. Most (actually I think all) of my users who use protonmail are scammers trying to sell fake goods - therefore banned. I might even ban all with @protonmail.com.
Do you think that reflect poorly or well on ProtonMail's trustworthiness?
I'm thinking it doesn't matter if ProtonMail's technology is trustworthy if the users are using it for untrustworthy purposes. Tor browser technology might be fancy, but expect the end IPs to be blacklisted or recaptcha'd to death. If you use mailgun (instead of a more restrictive service like Postmark) expect your emails to go to the junk folder. ProtonMail may share the same fate.
Maybe flag seller accounts with that mail so they're at a lower tolerance for abuse? Seems a bit overreaching to ban an entire email provider over some bad actors.
yeah that’s how we are doing it now. Flagged and then manual review. Often the same bad actors will just generate a new protonmail account... which leads us to browser fingerprinting
Protonmail is one of the few mailers that allow registration over Tor. I like that, because I value my privacy, but of course this also opens up abuse.
how about custom domains? are they more or less trustworthy than a gmail/hotmail/yahoo account?
On our website, custom domains are usually an employer domain and are rarely scammers.