Let us consider that you are using an email verification tool. It tells you that an address is valid or invalid. Do you know that this result given by the tool does not come from a simple format check or a lookup table? Yes, it comes from a live conversation with the mail server of the recipient, with the help of the same protocol that email has depended on for many decades now. It is known as the Simple Mail Transfer Protocol or SMTP.
If you are engaged in email marketing, it is important to understand the working of SMTP email verification. This is important for two reasons. The first reason is that it is more dependable compared to other methods to check deliverability. The second reason is that it shows the real restrictions of SMTP checks and why the accuracy of a tool depends on steps beyond the SMTP handshake.
SMTP Email Verification – What Is It?
SMTP email verification is the process of checking whether an email address is deliverable. This checking is done by connecting to the mail server of the recipient with the help of Simple Mail Transfer Protocol (SMTP) and asking whether the target mailbox will accept the email. This is done without actually sending a message. The response of the mail server to this query decides whether the address is greylisted, catch-all, temporarily unavailable, invalid, or valid. It is the most accurate method used for verifying email addresses as it queries the authoritative and live mail server directly.
How Does SMTP Email Verification Work?
An SMTP email verification follows a pre-defined sequence. For instance, at the first instance, the verification tool carries out a DNS lookup. This is done to find the MX records of the domain and spot the responsible mail server. Then, it will open a TCP connection to that server and will introduce itself using the HELO or EHLO command. It then declares a sender address with MAIL FROM and issues the RCPT TO command with the target email address. The response of the server to RCPT TO will decide the result with a code. For instance, a code 250 denotes the presence of a mailbox, while a code 550 denotes its absence. Thereafter, the tool closes the connection with QUIT. This happens without delivering any email to the recipient’s address.
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Why Is SMTP Email Validation the Standard for Quality Email List?
As you are engaged in email marketing, you should remember that every email you send to an invalid address will bounce. In the same way, every bounce will damage your sender’s reputation. Each hit to your reputation can reduce inbox placement for the email marketing campaigns that follow. The consequences one after the other from a dirty list are not only direct but also compounding.
This chain is broken by the SMTP email verification mechanism. It reaches the authoritative source, the mail server of the recipient, and returns a real-time and live answer about whether delivery is possible. No other technique gets closer to the truth of whether an email address is deliverable.
