Principles of verifying email addresses

LetsExtract Email Verifier offers 10 methods (options) of verifying email addresses. You can enable or disable the verification options in the Settings window.

Only options of group 1 are used in the Quick verification, options of groups 1 and 2 are used in the Full verification mode. Checks of group 2 are performed by scripts on your server in the Full verification (via scripts) mode.

 

Characters of an email address are checked. Valid characters are "@", ".", "-", "_", "0-9", "A-Z", "a-z". It is a very quick way of verifying (over 100,000 email addresses per second), which does not require an Internet connection. Examples of addresses that won't pass verification are john,doe@gmail.com, gates$microsoft.com.

 

Users often do not want to specify their real email address and use "random" combinations of characters or well-known phrases. Email Verifier will also mark such email addresses as Invalid. Examples: 123@123.com, fksdfaas@mail.com, john.doe@gmail.com

 

Some users are interested to get corporate email addresses rather than those registered at free email services like gmail.com, outlook.com, mail.com, etc. Such email addresses are marked as Invalid, if this option is selected.

 

There are services that allow you to create an email address for a very short time or to receive only one incoming email. Such addresses do not make sense for sending emails. Examples: Examples: 10minutemail, Tempmail, Mailnator, Guerrilla. Addresses from these domains will be marked as Disposal. You can change the list of disposable mail domains on the Disposable domains tab in the Settings.

 

Email addresses are marked as Invalid, if they match with the words from the built-in black list. Usually black lists are used to filter out spam filter markers, for example abuse@, forspam@, reports.spamcop.net and well-known junk email addresses, such as Rating@Mail.ru, noreply@, etc.

 

Email addresses containing obscene words are filtered out.

 

The program will check that the domain from the address exists and has an MX record in the DNS. This method works slower than the syntax and its variations (see above), but much faster than checking the existence of the email address on the server. Up to 25% of email addresses are usually filtered out at this stage of verification.

 

While checking an email address, Email Verifier tries to open a website (using the HTTP/HTTPS protocol) of the email domain. For example, for such email address as info@letsextract.com the URL will be https://letsextract.com/. If the site does not exist (a connection error was received), the email address will be marked as Invalid.

 

This option is used in Full verification modes. The program (or script) initiates a connection to the mail server of the MX record of the email address domain through the SMTP protocol and tries to send an email. If the server replies that the recipient's alias does not exist on the server, then that address will be marked as Invalid. For each verified email address, the connection protocol is saved by the server on the Log tab. It is the most reliable way to check email addresses for existence, but it is also the most time-consuming. There is also a risk to get banned by IP address/hostname.

 

Some email servers receive emails for any recipients. So if the email address has been verified at the previous step, this option allows you to find out an operating mode of the recipient server. To do this, Email Verifier tries to send an email to a randomly generated alias of the domain of the email address being verified. If the server replies that the recipient's alias (randomly generated) does not exist on the server, then such address will be marked as Valid. Otherwise it will be Indefinite. The program will remember the result and will not perform verification of other email addresses on the same domain.