As we discussed in our previous article, inbox rate (deliverability rate) monitoring is much more important than delivery rate monitoring.

In this article, I want to talk about seed lists and why they may not be the best tool to use to monitor your inbox rate. They ARE important and useful, but should only be used as one data point!

What is a seed list?

A seed list is a list of email address that are either owned by you or, is owned by a monitoring service. They are added to your regular list and mailed to along with the rest of your list.

Either you go check the placement of your messages in each seed account, or in the case of a monitoring service, they will check the placement and provide you with a report.

It is common to have more than one address at the major mailbox providers like Gmail, Yahoo, Outlook, AOL, etc.

Several of the mailbox providers will have regional providers as well like, so, if you do build your own seed list it is a good idea to get accounts at all the various regional inbox providers as well.

Important things to bear in mind with your own seed list.

NEVER interact with any of the messages. Don’t open them, don’t delete them, don’t mark them as not spam, mark them as spam, or anything else that will teach the mailbox provider’s filters what your personal preferences are!

Remember that each mailbox provider has their own, very intelligent, and learning algorithms, which will learn from your interactions with messages and based on it’s learning, place the messages for your seed account. These algorithms learn and act on a user level as well as on a global level. Your interactions with email will have the algorithms placing the same message for you differently than it does for the next user.

Problems with seed lists.

As mentioned above, the mailbox providers will learn what YOU like, and based on that, place your messages in the appropriate folder.

Let’s say your seed account receives a message which would normally land in the spam folder, but, in the past, you have opened email from that sender, clicked a link, filed the message in a folder, replied to the message, marked it as not spam or added the sender to your safe sender list. Because of your past actions and interactions with the sender, the message is now placed in your inbox instead of the spam folder.

Herein lies the biggest issue with seed lists. ANY real interaction with a message from a specific sender will influence the filters in a positive light, but, only for the account in which the interaction took place!

This is not the only issue with seed addresses though.

Mailbox providers will put the same message, to different subscribers, in different places.

Let’s say you send a message to 4 seed accounts at Gmail. It is highly likely that Gmail will place some of those messages in the inbox and some in the spam folder. This is especially true if you as a sender, or, your sending infrastructure is new to Gmail. Their algorithms have to learn from the actions of its users whether you as a sender is trustworthy or not.


Seed lists are a good tool, but, it should not be the only way that you monitor and track inbox placement.

You need to keep a close eye on opens and click from a specific mailbox provider, keep baselines for each mailbox provider and deep dive potential issues when your open and click rates suddenly drop on any particular provider.

One of the very first things you need to get your subscriber to do is to add your from address to their safe senders list to ensure the best possible inbox rate at an inbox provider. The more subscribers do this at a particular inbox provider, the better your inbox rate will be at said provider.