Some of the online Tools to check Mail ID validity.
Above Websites/Tools checks the genuine Email ID by the following common methods.
(Sender Policy Framework) SPF allows to specify which domain are allowed to send email from a given domain by creating DNS SPF record in the public DNS. The Mail exchanger then checks with the public DNS for the SPF record. IF this is in allowed list, then the mail is authentic else it is regarded as Spam.Eg SPF record: v=spf1 include:spf.visolve.com ?allDKIM
DKIM (Domain Keys Identified Mail) is a method to verify that the messages/Mail trustworthy, meaning that they weren't changed from the moment the message left the initial mail server. This additional layer of security is achieved by implementation of public/private key signing process. Since DKIM uses a keys, public key and a private key - the signing Mail Transfer Agent (MTA) generates a public key, which is published in DNS, and a private key, used to sign all the sent email messages.
The verifying MTA on the Receiver end retrieves the public key and compares it to the digital signature of the received email. If the key pair is a match, then the email is legitimate and is accepted by the ISP. Otherwise rejected.Eg DKIM key : v=DKIM1\; k=rsa\; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCrLHiExVd55zd/IQ/J/mRwSRMAocV/hMB3jXwaHH36d9NaVynQFYV8NaWi69c1veUtRzGt7yAioXqLj7Z4TeEUoOLgrKsn8YnckGs9i3B3tVFB+Ch/4mPhXWiNfNdynHWBcPcbJ8kjEQ2U8y78dHZj1YeRXXVvWob2OaKynO8/lQIDAQAB\;DMARC
(Domain-based Message Authentication, Reporting and Conformance)
DMARC enables the message sender to indicate that their messages are protected with SPF and/or DKIM. A DMARC policy applies clear instructions for the message receiver to follow if an email does not pass SPF or DKIM authentication—for instance, reject or junk it. If it fails or succeeds it will notify the sender that his message is accepted or rejected with info. Since DMARC leverages both SPF and DKIM it is highly secure way for mail authentication check.Courtesy: http://www.mcafee.com/ http://www.zimbra.com/