Problem
Marketing Pro email campaigns can appear to have been sent to a smaller audience than expected due to several different factors, such as audience or suppression settings.
Solution
To resolve this issue, try the following steps:
Check the Marketing dashboard date range
The Marketing Pro dashboard defaults to only show analytics within the last 30 days. Check the campaign's launch date to see if it's within the last 30 days. If it's not, adjust the dashboard date range to include it.
Go to Marketing
> Pro Campaigns.Select the campaign in question.
Locate the campaign's Launch Date.
In the side menu, select Marketing Overview and check the date range set for the dashboard.
If needed, adjust the date range selected on the dashboard to include the campaign's launch date.
If the number of sent emails doesn't increase or the launch date is already included in the dashboard's date range, go to the Clone campaign and check the audience reach breakdown section.
Clone campaign and check audience reach breakdown
To better understand your potential reach for an email campaign, clone the affected campaign and then view the audience breakdown on the Select Audience step. This breakdown helps you see how many of an audience's email contacts are reachable for a campaign.
The breakdown shows you if your audience reach is affected by factors such as:
Customers who don't have an email address on file.
Customers who manually unsubscribed from your company's marketing emails.
Customers who are automatically opted out of campaigns due to your Marketing Pro suppression settings.
Go to Marketing
> Pro Campaigns and locate the campaign in question.Click More
> Clone for the campaign. 
Click Edit for the Audience.
Review the breakdown for the selected audience. This provides insights as to why some or all of the customers in the audience may not have received the campaign email.
If the audience reach breakdown is not lower than expected, please contact Technical Support for assistance. If the audience reach breakdown is lower than expected, go to the Check email suppression settings section.
Check email suppression settings
As seen in the above section, the actual audience reach of a campaign can differ from the potential reach depending on how your Marketing suppression settings are configurated.
Check the Marketing Pro settings to see if either Double Opt-In or Double Opt-Out are enabled. These settings help improve deliverability from your email domain and help reduce spam rates. However, they can automatically suppress customers from receiving campaign emails even if they meet all the audience inclusion criteria.
Check your Double Opt-In settings
Go to the top toolbar and click Settings
.In the side panel, go to Marketing Pro > Marketing.
Scroll down to the Double Opt-In section.
If the Double Opt-In setting is on, customers must have the Opted In tag to receive marketing emails. To find out why a customer didn't receive an email, check their profile for a missing Opted In tag. If it's missing, this is the reason they didn't receive the marketing email.
Note: The Opted In tag is automatically applied if customers choose to opt-in. You can also manually add the tag to a customer's profile if they provide consent. This consent is required to be compliant with CAN-SPAM laws.
If you want to send marketing emails to customers without the Opted In tag, turn the Double Opt-In toggle off.
If Double Opt-In is not enabled, check whether or not Opt-Out Message is enabled in your Marketing Pro settings. If Opt-Out Message is enabled and the Auto-suppress dormant emails option is selected, then customers that are tagged as Email Dormant can still appear in audiences but will not receive any marketing emails.
Check your Opt-Out Message settings
Go to the top toolbar and click Settings.
In the side panel, go to Marketing Pro > Marketing.
Scroll down to the Opt-Out Message section.
If the Opt-Out Message setting is on, customers with the Email Dormant tag will not receive marketing emails. To see why a customer did not receive an email, check their profile for the Email Dormant tag.
Note: The Email Dormant tag is automatically applied when Auto-suppress dormant emails is selected and a customer does not open a marketing email within the customizable timeframe. The tag can be manually removed from a customer's profile if they provide consent.
You can turn the Opt-Out Message toggle off to send marketing emails to all customers, as long as they aren't suppressed in any other way.
If you disabled any of the above suppression settings, you can clone the original campaign, re-create the audience from scratch, and launch the new campaign. Make sure to stop the original campaign if it's still live.
Tip: Add a Marketing Behavior exclusion filter to the audience of the cloned campaign to exclude any customers that were sent content from the original campaign.
If the suppression settings were not the issue, go to the Check audience age section.
Check audience age
For an audience used in a previous Marketing Pro campaign, the recipient list is set at the time the first campaign is launched.
If you reuse the same audience for a new campaign, the recipient list will not automatically update, even if the total audience reach appears correct.
To update the recipient list, you must:
Clone the original campaign.
Create a new audience.
Launch the cloned campaign with the new audience.
Make sure you stop the original campaign if it is still live.