Create an ad unit
Set up one ad slot in your newsletter, with its placement key, format, accepted sizes and floor price.
Updated 2026-11-02
An ad unit is one slot in your newsletter, such as a header banner or a mid-issue block. Each slot gets its own ad tag.
Before you start
- You need the Owner, Admin or Manager permission on the publisher account.
- Decide where the slot sits and which ad shapes fit your template.
Steps
- Open Ad Units and select New Ad Unit.
- Enter an Ad Unit Name, such as Header Banner.
- Enter a Placement Key. This identifies the slot inside the tag, for example
daily-brief/header. - Choose an Ad Format: Banner, Native, Sponsored or Interactive (AMP for Email).
- For a banner or sponsored slot, choose the Accepted Ad Sizes. All standard sizes are ticked by default, so untick what your template can't hold. Select + Add custom size for any other size.
- For a native slot, choose its size and colours and check the Preview.
- Set Floor CPM ($) if you want a minimum price. See Set a floor price.
- Select Create Ad Unit.
Banner sizes
| Name | Size |
|---|---|
| Leaderboard | 728×90 |
| Medium Rectangle | 300×250 |
| Newsletter Rectangle | 350×250 |
| Billboard | 970×250 |
| Hero / Showcase | 970×550 |
An image ad shows in a slot only if its size is one the slot accepts. The fewer sizes you accept, the fewer ads can fill the slot.
Native sizes
A native ad is drawn in your slot's style at one fixed size, and text is cut to fit.
| Name | Size | Layout |
|---|---|---|
| Card | 600×480 | Image on top, text, logo and button |
| Medium Rectangle | 300×250 | Image, headline, logo and button |
| Split | 600×200 | Square image left, text right |
| Text only | 600×160 | Text block, no image |
Which format to choose
- Banner takes image ads and is the only format third-party DSPs can bid on.
- Sponsored uses the same tag and takes the same ads as a banner slot.
- Native takes native ads only.
- Interactive runs in the AMP part of your email. Set up your sending first under Interactive Setup.
What happens next
The new unit is Active straight away and shows in the table with its key. Its next step is the ad tag.
Use the buttons on each row to edit the unit, get its code, pause or resume it, or delete it. A paused unit shows no ads until you resume it.
Changing a placement key, or deleting a unit, breaks any tag already in your template for that slot. Tag Health then reports Unknown ad unit. Re-copy the tag after a change.
If something goes wrong
- "Select at least one ad size." Tick at least one size for a banner or sponsored slot.
- "An ad unit with placementKey … already exists for this publisher". Each key can be used once in your account. Choose another.
- "A native or interactive ad unit's placement key cannot contain '/'". Use
-or_instead, for exampledaily-brief-mid.
Related
Still stuck? support@mailadx.com