This is largely an issue with top level domains. Things outside of .com/.org/.net tend to get flagged as non-viable email addresses, because it doesn’t fit the specific “@.com” format that the site has programmed their scripts to look for.
Also, spammers and scammers often tend to use TLDs outside of the big three, because the domains tend to be cheaper when they don’t end with “.com”. So the spammer is able to buy and cycle through their domains much faster, because they’re saving money with every single domain registration.