Test Removing Generic, Role-Based Email Addresses
There is a great deal of evidence to suggest that the longer marketers keep inactive email addresses on their list, the more likely they are to potentially damage their sender reputation.
While most email service providers do an excellent job of helping marketers remove invalid addresses and some even go as far to provide solutions to help sender identify inactive subscribers, there is one group that often make up majority of recipient lists and they can be the root cause of deliverability problems - the generic, role-based email address.
Consider your own "enterprise" for a moment - it's not uncommon for prospects to use generic email addresses such as support@, info@, webmaster@, etc., when subscribing to something (like a newsletter or when they want to download something). The problem is, these generic, role-based (intended for a specific person or group of people) are usually just going to one person and are used so personal email addresses aren't shared with brands/businesses. The problem is that the one person receiving that generic email address may never, ever even open the email being sent by the marketer.
The counter to this is that those with "real" address (containing names, either first or last or some combination) are typically actual people that subscribed and those who are interested in a particular offering.
Consider this basic optimization practice if your deliverability rates are lower that you'd like to see. Filter your list by those with "known" role-based email addresses (info, general, support, social, webmaster, sales, etc.) and compare the open and click-through rates on the past few email sends to determine if this segment of your list is causing poor performance. The answer will likely be a resounding "yes" for most enterprises.