An advertiser sets up a Conversions campaign with three ad groups. Each group targets customers who previously added items to their cart, using keywords and customer mailing lists to do so. After the campaign has been “live” for two months, the advertiser notices the campaign is under-delivering.The advertiser checks each ad group's performance and sees that the targeting customer mailing lists did not spend in the last five days. What should the advertiser do first to help the mailing list ad group deliver?

When a specific ad group—especially one using a Customer mailing list—suddenly stops spending or delivering, the most likely cause is an issue with the audience itself. Audience Size Requirements: Pinterest requires a minimum of 100 matched users for an audience to be active. If your mailing list is too small or if the "match rate" (the number of email addresses that correlate to active Pinterest accounts) is low, the ad group will fail to deliver. Audience "Health": Over time, custom audiences can become stagnant. If the list was uploaded two months ago and has not been updated, the "pool" of eligible users who haven't already seen the ad or converted may have been exhausted. Verification: Before changing your entire campaign objective or creating new ad groups, you must verify that the audience status in the Audience Manager says "Ready" and that the size is large enough to support the bid and budget. If the audience is too small, Pinterest's system will stop serving ads because there are no more eligible people to show them to.