Email Validation to Improve Deliverability

by | Nov 10, 2014

How can you decide if an email address has a valid opted-in address or not? It is imperative for your reputation that you do not spam! Protecting your sending reputation helps your valid email addresses get delivered and keeps you off the blacklist of spam filters. It is very important to remember that emailing to addresses that did not opt-in is a major cause of delivery issues. Delivery issues can occur on the list itself or based on other users of the same server. Thus, the validation process should be followed by all users of that server’s email marketing platform.

The following is a description of a simple process for validating your email list.

Each part of an email address is inspected as it goes through a validation process.

The parts are as follows:

  • Local Part – the part of the email address before the @ is inspected. Example Jsmith of
  • Domain Part – the part of the email address after the @ is inspected. Example of
  • Entire Address – the entire email address is inspected.

Inspecting the Local Part

The local part of an email address is inspected for a match from one of the local parts listed below. If the local part of the email address is listed below, then the email is considered invalid.

Here are the local parts that should never be emailed:

abuse intrusion pager
biz dev investor postmaster
board investor.relations security
contact investor-relations smtp
contact_form investors subscribe
contact-form jobs support
critical listserv test mailer-daemon unsubscribe
dns mailing-list usenet
dns-admin news uucp
ftp nntp webmaster
hostmaster noc whois
inquiries orders www


Again, these local part should never be on a list that is opted-in, as they are either spam traps or they are for administrative purposes only. Basically an email address that belongs to a group of people and not an individual can be seen as spamming as one person cannot opt out.

Inspecting the Domain Part

Some of domains that should never be emailed are listed below. Each one used to be a valid domain, but are no longer considered valid. Thus, an email address with one of these domains is invalid and probably has been invalid for at least 5 years.

Here are some domains that should never be emailed:


Again, these domains should never be on a list that is opted-in; these domains should never be sent an email, as they have been invalid for over 5 years.

In addition to spam filters inspecting the domain part of an email address for domains like those above, the spam filters checks to see if a valid MX record for the domain exists.

What is an MX record?

From Wikipedia, a mail exchanger record (MX Record) is a type of resource record in the Domain Name System that specifies a mail server responsible for accepting email messages on behalf of a recipient’s domain.


If an MX record does not exist for a domain part, then that email address is invalid and should not be sent to. Most invalid email addresses are invalid because of no MX record due to the misspelling of the domain. There would be no valid MX Record for or yahoo.coom, for example.


By making sure your email marketing program uses validation, you can make sure your reputation is kept clean and your emails have a better chance of being delivered.


Next blog article will cover validating the full email address and some other steps in the process.