Before I get into email business(I run my own email forwarding service[0]), I don't understand why provider block those domains.
Then I immediately got it. The amount of spam emails from .xyz .click .faith .top is huge. And with every email comes from them, we have to run spam scanner, which isn't cheap. So we have to score those TLDs more sensitive.
> We should have known better from the beginning as we previously founded Outreach.io, the leading sales engagement platform, making us no strangers to email deliverability. In the early days of Outreach, we had utilized some short .xyz domains to use for shortened links in emails sent on behalf of our customers.
Translation: We used .xyz for spamming, of course .xyz is associated with spam.
Then I immediately got it. The amount of spam emails from .xyz .click .faith .top is huge. And with every email comes from them, we have to run spam scanner, which isn't cheap. So we have to score those TLDs more sensitive.
https://www.spamhaus.org/statistics/tlds/ can give some insight about spam rate by tld.
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[0] https://mailwip.com