How to check whether an email address exists

email

I'm trying to check 2,000 email addresses to see whether they exist. Are there ways to check whether an email address is valid without sending email to each address?.

I found an online service Email Unlimited, but it only checks 20 email addresses before having to buy the full version.

Best Answer

Just for the sake of completeness: some SMTP servers do indicate if an email address exists. Following a full example in another answer:

telnet gmail-smtp-in.l.google.com 25

helo example.com
mail from: <me@example.com>
rcpt to: <somenonexistinguser@gmail.com>
550-5.1.1 The email account that you tried to reach does not exist. Please try
550-5.1.1 double-checking the recipient's email address for typos or
550-5.1.1 unnecessary spaces. Learn more at
550 5.1.1 http://mail.google.com/support/bin/answer.py?answer=6596

Upon success, and on servers that cannot or do not want to tell if an address is valid, the last command would yield:

250 2.1.5 OK

One could then simply invoke quit without sending any email at all. Still, when trying many addresses, this might also get you blocked.

(Gmail does not support the vrfy command. On the website, it also has a "check availability" button when signing up for a new Gmail account. That could also give you some information, but old addresses will be unavailable for some time.)