Manual for Mail Verifier: Email addresses verification

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Several types of email addresses checkup can be performed. The number of methods affects checking quality and overall time of validation process.

Verify syntax

Syntax checking consists of checking e-mail address for “@” availability and for allowed characters. The allowed characters are: “-“, “.”, “0..9”, “@”, “A…Z”, “_” and “a…z”. This checkup method is the fastest with average speed of checking and it verifies thousands of e-mail addresses per second. However, we recommend using it for huge mailing lists only just to make sure there are only validly spelled addresses in the list. Internet connection is not required for using this method.

Verify domains

Domain checking is performed by connecting to DNS servers and querying domain names of e-mail addresses (e.g. checking domain.com for existence of kate@domain.com email address). Checked domains are marked in domains list in the following way:

– if the domain name is invalid or exists but does not have MX records it is marked as “Domain doesn’t exist”

– if the domain name exists and has MX records it is marked as “Correct” or “Mail exchange server exists”

The speed of this operation is lower than in case of syntax checking. This method is recommended for mailing lists containing hundreds of thousands or millions of email addresses. About one third of invalid addresses are removed on this stage of checking.

Verify email addresses

The complete e-mail addresses checkup is performed by connecting e-mail server(s) specified in domain’s MX records, returned by DNS server during querying or directly to the domain name mail server in case when MX records are not found. Upon connecting to server the program tries to send mail to email address being checked for validity. If the server responds with mailbox available message the email address is marked as “Correct”, otherwise as “Invalid” — no mailbox. The conversation to SMTP-server is displayed on the right log-panel located. Syntax checking and Domain checking methods are used prior to Complete SMTP checking.

This type of checking gives the most realistic results, however it takes reasonably more time to complete such check. The Complete SMTP checking method is recommended for mailing lists with no more than a hundred thousands of email addresses. About two thirds of invalid addresses are removed on this stage of checking.