My email was not sent: a troubleshooting guide

Level 10

One of the recurrent question we face from Marketo users is "Why is there such a difference between the number of leads in my target and the number of emails actually sent". This can be explained my multiple, non exclusive factors that all can be identified and measured.

Some bad guys were part of your target:

You have not excluded a whole series of leads from your campaign: the blacklisted, the empty emails, the invalid emails (previous hard bounces), the unsubscribed and the not-so-ugly marketing suspended ones. If you have not done so yet, create a smart list in you lead database, name it "Global Exclusion List" and add all these filters to it, with a "ANY" (OR) rule logic:


Then create another smart list in the program that hosts you email campaign with the 2 following filters:

  • "Member of smart campaign" IS [The smart campaign that was supposed to send the email] (could be replaced by a member of program if it's an email program)
  • "Member of smart list" IS "Global Exclusion List"

That smart list will give you the list of leads that were excluded by Marketo from the email cast.

And BTW, since you now own the "Global Exclusion List", make it mandatory to all users to always add a "member of smart list" IS NOT "Global Exclusion List" to all your campaigns.

Some of your leads were hit by the communication limit:

This is the reason that users who started to use Marketo recently tend to forget the most easily. Remember, some limits are set to prevent you from overloading your prospects mail boxes, and apparently rightfully And guess what, Marketo does enforce these rules! As there is no filter that can give you the list of emails (Vote here: ); detecting them is a little tricky. You will have to go the smart campaign that was supposed to send the email and the click on the "Results" tab. Finally, at the bottom, enter "communication limit" in the search box:


The list of leads that were impacted will show up, and the count will be visible at the bottom-right corner of the screen. Remember here that communication limits are evaluated per day (based on the calendar day in the subscription time zone. (midnight-midnight)) and per rolling period of 7 days. You can override these communication limits in a smart campaign, but use this with extreme care and monitor closely your unsubscribe rates when you do so (on all emails sent within the same period of time).

Some of the leads were in fact duplicates

Marketo takes care of you: as sending the same email twice to someone is not really a commonly accepted best practice, if Marketo detects 2 or more duplicates in your smart campaign target, it will automatically remove the superfluous ones from the email cast. These are quite easy to list. Create a smart list with the following filters:


And remember that Marketo did not remove all the leads in this list: it sent email to one lead for each set of duplicates in the campaign and skipped the others.

The hard point about duplicates is that you cannot exclude them from your campaign preventively: if you add a "Duplicate field is Email address" filter, it will exclude all of them, not just the redundant ones.

Of course, all this would be made easier if it was possible to filters leads for which an email was targeted but not sent:



Grégoire Michel we are also using a marketable list for all our emails so usually our target numbers are pretty close to our sent numbers. However I don't get your mention about duplicates. You cannot have duplicates within a smartlist, can you?

Bonjour Cécile,

Yes you can have duplicates in a smart list. Let's say you have 2 leads in your smart list with the same email address. Marketo will only send 1 email, but you will have 2 leads in the target, and therefore there will be a difference between the target and the number of sent emails.

The hard point is that you cannot preventively remove them, as if you use a "Duplicate fields" filter in your target, you might exclude all of them, not just the redundant ones.


Not applicable

Beautiful response to a very common question! I have bookmarked this to relay to our requestors for education as we always get this question - thank you!

One more thing to mention here (mostly related) is that Marketo will only dedupe on batch sends, so if you have a triggered campaign, it's possible that the duplicate would be able to receive the same email as many times as their record exists in the database -- even if you have set it so that a person can only flow through one time.

Yes. The moral of this story is to avoid or remove duplicates from your database! I have to say that at Talend we are getting pretty good at doing that but we also have the luck to have our own tools to help.

Not applicable

Very useful answer. We all get these questions from time to time from our business users.


Level 5 - Champion Alumni

Also as far as I am aware if you do have duplicate email addresses Marketo will send it to the lead record with the most recent activity. There is a small caveat but I can't recall that right now.

Level 10 - Champion Alumni

That's a great point, Dory - something I think many users forget.

Hi Dory,

So true!

The post was about emails not sent, not about emails sent twice


Not applicable

Hi Gregoire

Any chance you'd be able to view my issue?? I have it posted in the link below. I looked at your above and I do not fall into any of that:( this was an internal email and all things said that the send would be to 78 and it only did 48. Any insight would be wonderful. Thank you.

Help - not all in email list were emailed.... Grégoire Michel