Seeds

While seed lists have forever been known to test emails before everyone out there gets it, we allow you to use a seed list for verifying the campaign content at its launch time before the rest of your intended audience receives the campaign. You can add internal users, key stakeholders, external agencies, test email accounts, and many more to your seed lists. Here's how you can create and maintain multiple seed lists on the ZMP:

1. Navigate to Settings > Audiences > Seed Lists. Click on the New Seed List button at the top-right.

2. In the panel, add a Name to your list and an optional Description.

3. Click on Add Recipient then select the option to add manually or paste in a list of recipients.

You can also add an optional first and last name to your seed emails, and you can additionally edit, delete, or duplicate an existing seed list as needed by clicking on the list you want to edit or clicking the ellipses menu on the right.

If the email address is associated with a user in the seed list, that user will receive the seed email.

4. Once a seed list is created, it can be added to a campaign later. Multiple seed lists can be added to a campaign.

Dynamic Elements

For content with dynamic elements, ZMP will use any information stored in the seed list member's profile. If no relevant properties exist, defaults from your dynamic logic will be used instead. Another handy way to detect a seed list user in your dynamic logic is by using the hidden property is_seed_user. For example,

{% if is_seed_user %} For Seed's Eyes Only: {% endif %}

When do seeds get sent?

Standard broadcast

Seeds are sent immediately at the start of the campaign — before the main audience begins receiving messages.

During send processing, seed segments are prioritized first:

1. Seed recipients are computed before the primary audience

2. Seed messages are queued ahead of all other recipients

3. The seed batch is flushed immediately

Seeds are not distributed gradually throughout the send.

A/B test (multivariate / multiversion)

Each variant maintains its own audience configuration and associated seed list.

As a result, seed recipients receive:

• One email per variant

• At the beginning of each variant’s send

If the campaign includes a winner-selection phase and a follow-up winner send, seeds configured for that send will also receive the winning version.

Throttled/metered/scheduled sends

Seeds bypass throttling and delivery-rate controls.

Even when the primary audience is released gradually over time, seed recipients receive their emails near the beginning of the send window and are not subject to volume limits.

Triggered / journey sends

Seeds can also be configured for triggered or journey messages.

When enabled:

• Seed recipients receive the message the same way a real recipient would

• The send is still flagged internally as a seed event for analytics filtering

This setup is less common than broadcast seeding. If you expect seeds on a triggered flow but are not receiving them, verify that a seed audience has been configured for the trigger or journey.

Additional behaviors and limits

Seeds are excluded from campaign analytics

Seed activity is filtered out of reporting and performance metrics, including:

• Opens

• Clicks

• Deliverability metrics

• Aggregate campaign reporting

Internally, reporting filters on is_seed = 0.

This behavior matches the in-product guidance:

“Seed lists allow stakeholders to know about campaign sends in real time. These recipients get the campaign before the target audience and aren't counted in campaign analytics.”

If reporting totals appear lower than expected by approximately the number of seeded recipients, this is typically the reason.

Custom seed lists are limited to 50 email addresses per version

Custom (ad hoc) seed lists support up to 50 email addresses per campaign version.

The API rejects attempts to exceed this limit.

Personalized seed-content limit: 2,000 members

When Use Audience Content for Seed is enabled, seed personalization is supported only if the combined seed segments contain 2,000 members or fewer.

If the combined seed audience exceeds 2,000 members:

• Personalized seed rendering is disabled for that send

• The send continues without seed personalization

This commonly affects large internal QA or stakeholder distribution lists and can be easy to overlook during troubleshooting.