Yahoo and Hotmail detection limitations

yahoo, hotmail, and other free email providers are notoriously difficult to detect and also deliver to only a few email verification providers can accurately detect yahoo owned email addresses these include yahoo, aol, and verizon domains mailfloss' deep clean engine is one of the few email verification services that can detect these and won't simply mark them as accept all as most services incorrectly do however, mailfloss cannot detect yahoo owned email addresses that are disabled mailfloss can only detect that the addresses exist and if it has been deactivated, but if yahoo disables an email address due to inactivity we aren't able to detect these the bounce reason looks like this "554 30 sorry, your message to email\@yahoo com cannot be delivered this mailbox is disabled (554 30) " this is normally not an issue except for old lists if a list is old, please be aware of this limitation and recognize that it might be better to quarantine yahoo email addresses from your main campaigns we can detect deactivated yahoo addresses, whose bounce code looks like the following "552 1 requested mail action aborted, mailbox not found" it's not entirely clear how yahoo distinguishes a disabled address versus and deactivated address, however, there has been an uptick in yahoo disabled addresses as the company has restructured in recent years