Not really. There are many things that can cause a false positive as well as false negatives.
Off the top of my head examples include:
- Mail server temporarily down
- Incorrectly configured spamfilter being way too aggressive
- Server running properly, but mailbox isn't receiving it (Happened on my server because of a config-screwup)
The only true indication that an address is working as intended is getting a reply from it. And even that might be temporarily. On the flipside, any issue reported when you try to reach it can also be temporary.
The only exception that I can think of is if the domain simply doesn't exist.
did you tryed just sending an email, if mails fails to send or user is unable to recieve you will have an answer from the server in your inbox. – Francisco Tapia – 2015-05-20T21:17:12.000
yes, but I believe that such notification is only returned if domain does not exist. – LucasSeveryn – 2015-05-21T15:11:39.820
No, if mailbox is full, server will give you a message – Francisco Tapia – 2015-05-21T15:16:17.593