What email addresses tell you about your users

When it comes to list hygiene there are lots of ways to identify poor quality profiles based on historical data:

Does the user unsubscribe or complain upon receiving your emails (which is the best reason of course to stop sending them)? Does the email bounce (hard or soft)? What is the softbounce reason (spam filtered, timed out, relay error,...)?
Does the user open emails you send to him? How long has he been inactive?

All of this needs some broadcasting before you can estimate the potential risk of each of these users on you deliverability and your email marketing campaigns efficiency.

But, before any broadcasting is made, some information about your profiles can be found according to the user's emails.

An email is made of 3 parts:
- The user name (or local part)
- The domain name
- The extension

Each of these parts can be looked at to get more information about the type of profile.

First the user name:
Here you should probably check the emails for bad words and insults, it's not very likely that someone would register to a list he really wants to get emails from with an email such as : spamthisemail@domain.com
Same thing for email aliases such as info@, sales@,... these emails are very likely to be received by several persons and probably one or the other will either complain or unsubscribe on the first email received (anyway it's not very likely anyone would have registered with such an email in the first place)(of course this is less relevant when talking about B2B lists).

Then the domain name:
If people usually have several email addresses, usually people check more often their ISP's or their professional email than their webmail accounts (mind this is no absolute rule).
You should also probably check your list for disposable email addresses, you can check my list of disposable email email providers.

Finally, the extension can give you a couple of extra information like the country of the user. If you run an US campaign you shouldn't probably be sending emails to .ru emails for example.