How to stop Marketo from sending to multiple contacts with the same email

[Alex_Baumgarten]

We are having an issue in our instance where we have duplicate contacts for the same person that utilize the same email address. I know that in Marketo, the unique identifier is not the email address, so it makes sense that this could happen. The issue is that now for batch sends, these users are receiving the same email twice. I've been told that Marketo has built-in logic to stop the tool from sending to the same email address more than once. But I don't think this is true because it is sending to both of the contacts even though the contacts have the same email address.

Has anyone seen this in their own instance? If so, any ideas on how to correct it?

[Josh_Hill13]

This isn't exactly what's going on.

1. Marketo does dedupe on email address, but only on direct imports, API, form fills. NOT SFDC or previously existing records.
2. If 5 Records enter the same BATCH at the SAME TIME (Same Run), Marketo won't send 5 emails to the same person at the Send Email flow step. It will realize the dupe and send one.
   1. But, with Triggers, the Records don't enter at the same time, so some email addresses could enter and get the same email several times if your Schedule rules are Every Time.

[Alex_Baumgarten]

Let me see if I understand exactly what you are saying.

1. Marketo does dedupe on the email address unless the contact is uploaded via SFDC or is an existing contacts.

2. For batch sends, Marketo will only send to one email address, even if the same email address is loaded into multiple contact records

3. Marketo will send to multiple emails via triggered campaigns because records are not feeding through the campaign at the same time, resulting in Marketo sending to the same address multiple times.

I looked into some of our duplicate contacts and it looked like a few duplicates were made and both were created in Marketo via an API integration.

[SanfordWhiteman · Accepted solution]

1. Marketo does dedupe on the email address unless the contact is uploaded via SFDC or is an existing contacts.

Well no -- actually Josh mentioned a few different ways that multiple people can have the same email address. Email address is not a primary key in Marketo, it just happens to be the deduplication (pre-insert) key for certain common upsert methods, such as Marketo form fillouts and UI-based list uploads.  API-based updates keyed on another field, SFDC syncs, and (important!) manual changes to the lead record or via flow steps do not check if the email address is used elsewhere.

2. For batch sends, Marketo will only send to one email address, even if the same email address is loaded into multiple contact records

Correct, as an anti-spam measure a given Send Email or comparable batch event will only send to one qualified lead with each email address.

3. I looked into some of our duplicate contacts and it looked like a few duplicates were made and both were created in Marketo via an API integration.

Duplicates are very easily created via API, but also can be very easily avoided. Depends on what the client app decides to dedupe on.

[Tyler_Hubbell]

Hi Sanford,

2. For batch sends, Marketo will only send to one email address, even if the same email address is loaded into multiple contact records

Correct, as an anti-spam measure a given Send Email or comparable batch event will only send to one qualified lead with each email address.

We have run into an issue where a batch campaign sent an email to an email address twice (since it is in multiple contact records that qualified). The Smart List only had an Email Address filter, and the Flow was just Send Email. Any insights into how this may have happened?

[Alex_Baumgarten]

Was there any sort of A/B test used for the batch send?

[Tyler_Hubbell]

Nope, there was no A/B for that send.