Technically there is, I think SMTP has 'VRFY' or similar to check if an email address exists. However I recall reading (like, over a decade ago) that it's often

Technically there is, I think SMTP has 'VRFY' or similar to check if an email address exists. However I recall reading (like, over a decade ago) that it's often not supported as it makes it easier for spammers to validate real email addresses.