In certain cases, our subscribers do not use unique email addresses (in cases of family members who share email addresses) - so we have addressed this by assigning our numeric 'account id' to the Exacttarget 'subscriber key'.

Additionally, for 'leads' we do not have an 'account id' because they are not yet members, so we have assigned their email address as their 'subscriber key'.

My first question - how can I segment my subscribers so I can quantify how many have a numeric (account id) subscriber key versus a text (email address) subscriber key? I'm looking at Data Filters and groups, but it doesn't seem possible to segment by subscriber key, nor to filter by a data type query.

Secondly - what are the downsides to having inconsistent subscriber keys? Is it worth the effort to come up with a solution to make all my keys use a consistent data type?

Thanks! Neil

2 Answers 2


Unfortunately it's not possible to use data filters with Subscriber Keys, so the best way would be to extract the data out into Excel and sort that way.

Inconsistent Subscriber Keys will lead to issues of unsubscribes and tracking. For instance, if a person unsubscribes as a Lead (with an email address as a Subscriber Key), and is thereafter converted as a Contact (with a AccountID as Subscriber Key) they will receive email communications as a Contact even after opting out. The best way to avoid this situation is to use different types of communication for both Leads and Contacts

Bounces will also be impacted, as Marketing Cloud manages bounces at a Subscriber Key level.


If I understand this correctly you have one field called "SubscriberKey" that can potentially store either data type as a key. To solve your current issue have you tried creating a Data Filter on the SubscriberKey, selecting "does not contain", and then entering the "@" character in the text box?

This seems messy, I feel like it could run into other headaches down the road. What happens when you have two pending clients with the same email address?

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