Read This Before You Send to an Old List!

There are times when you may be tempted (or legally required) to mail to an old list. For our recent Ask the Experts webinar, this topic was submitted more than a few times. My first reaction when I hear a client broach this topic is to cringe. For whatever reason you’re compelled to send it, it’s never pretty. If this type of campaign is on the horizon or on an upcoming agenda, read on. In this post, I’ll outline steps you can take to help mitigate the risks associated with this inherently risky type of send.

Weigh the potential risk versus the reward
If you’re legally required to contact an old or inactive list, skip down to the next section. If mailing to this list is a choice, I recommend that you think long and hard about the potential outcomes. Sure, you may revive a few otherwise dead addresses, but there is also a very good possibility that you are going to do damage to your reputation, hurting both your deliverability and total program performance. This is something that can even impact mail to healthy, engaged subscribers. Check out this post for some additional color on why sending to old files and inactives should give you pause. If mailing to an old list still sounds like a good idea, below are a few ways you can reduce the negative impact.

Start with a clean list
Email lists are NOT like fine wine. Chances are, that old list is going to be host to more than a few unknown users and spam traps. The extent will be dependent on the quality of the list before it got shelved and how long it’s been sitting around. Rather than finding out the hard way during your first send, I highly recommend working with a list validation service to remove problematic data before the deployment.

Ideally, run your list just before you start sending. This will allow you to purge hard bounces, some of which may have been converted into unknown users after prolonged periods of inactivity. The list validation process can also give you an idea of the quality of that old file. If you have a high ratio of unknown users, proceed with caution. This is going to be a good indicator that your list may also have a higher number of spam traps.

Despite rumors you may have heard, list validation services are not going to be able to rid your list of spam traps for you. This would defeat the purpose of spam traps in the first place, which is to allow mailbox providers to identify senders with poor mailing list hygiene practices. Check out this Zombie-themed blog post one more time for more details on spam traps.

Consider Quarantines and Send Strategically
Now that you’ve done what you can to clean up your list, you still need to be very careful about how you proceed. This is especially the case with segments of your list that have been suppressed from receiving messages from you for an extended period of time. In addition to a greater likelihood of spam traps, your old list is also going to be more likely to trigger spam complaints from users and show very low engagement. The combination of these factors is a great way to raise a red flag with mailbox providers and negatively impact your IP address and domain reputation.

That being said, you want to be careful with the IP addresses and domains you use to send. There are two primary approaches to this.

  1. Send many small volume campaigns over a long period of time and intersperse these campaigns with high-engagement messages to good quality subscribers. By balancing small portions of the bad with large portions of the good, you may see minimal impact and actually get some of these poor campaigns into the inbox. Using this approach, you would most likely want to select high volume IP addresses. If you follow this approach, monitor your placement very, very carefully. If you see a drop in performance, you’ll need to pull back or resort to option 2.
  2. Designate a specific IP address and use it to quarantine mailings to the old list. If you have to do a single large blast or email a high number of old/inactive subscribers in a very short period of time, you may need to use this approach and potentially sacrifice an IP address for the safety and performance of other IP addresses. If you go in this direction, consider mailing to your most recent/best addresses first as those will have a higher likelihood of making it to the inbox. As your send continues, mailbox providers may start routing messages to the spam folder or may even start blocking your messages.

If possible, test
If you can, send a small test deployment to a random portion of your old list. Watch your results carefully to determine how to proceed with the remainder of the list. If you’re sending by choice, review the engagement level of the campaign as well as negative metrics like complaints and unsubscribes. If you saw minimal engagement and conversion rates you may want to use this as evidence that a broader send will likely be more trouble than it’s worth.

Monitor and react quickly
Once you’re ready to deploy, whether it’s one big blast or several smaller sections, it’s important to monitor carefully. Loop in your email service provider so they can help with damage control if need be. If you’re working with Return Path, let your account manager know as well. Watch your inbox placement, complaint rates reputation, and bounce logs. If things start to go south, consider pausing your deployment and rethinking your strategy.

Check out our Ask the Experts webinar to hear a Return Path panel of email experts answer tough deliverability questions.

minute read

Popular stories



BriteVerify email verification ensures that an email address actually exists in real-time


The #1 global data quality tool used by thousands of Salesforce admins


Insights and deliverability guidance from the only all-in-one email marketing solution

GridBuddy Cloud

Transform how you interact with your data through the versatility of grids.

Return Path

World-class deliverability applications to optimize email marketing programs

Trust Assessments

A revolutionary new solution for assessing Salesforce data quality


Validity for Email

Increase inbox placement and maximize subscriber reach with clean and actionable data

Validity for Data Management

Simplify data management with solutions that improve data quality and increase CRM adoption

Validity for Sales Productivity

Give your sales team back hours per day with tools designed to increase productivity and mitigate pipeline risks in real-time