Sending a Mailing

Once a mailing is configured and the message is composed, the mailing is ready to be sent. On the summary page for the mailing, click Send Mailing. A Send Mailing popup will open to define the type of Deliver campaign and the delivery instructions.

Before sending the mailing, it is a good idea to display a sample message and send a test message. Use the links in the action items column to manage these tasks.


One Time Campaign

To send a one-time mailing campaign, use the settings described here, but be sure that the Ongoing box is not selected.

  • Pre-Flight Checks: Any errors or warnings that identify any common mistakes in the mailing setup will appear here. Errors prevent the activation of a mailing, but warnings will still allow the mailing to be sent. For example, if the Recipient field is missing an email address, an error message will appear. If a merge field exists in the message body, but it is missing from the recipient list exports, a warning will appear, but the message will still send.
  • Estimated Recipients: Shows a summary of the expected delivery report before sending.
  • Recipient Lists: Review the recipient and suppression Lists.


  • Ongoing: Important - leave this box cleared if this is a one-time mailing.
  • StartDate/Time: Optional. If desired, schedule a start date and time for a one-time mailing. If the message is to be sent immediately, leave these fields blank.
  • Send Mailing: Click to activate the mailing.
  • Save Settings: Click to save the settings without sending the message.

Ongoing Campaign

An ongoing campaign has the same setup as a one-time campaign, with the additional step of selecting the Ongoing option. Selecting the Ongoing box will display additional delivery options:

  • Ongoing: This box must be selected to run an ongoing email campaign.
  • StartDate/Time: Define the start date and time for the email campaign.
  • StopDate/Time: Define a stop date and time for the email campaign. If this section is left blank, the campaign will run until it is manually stopped. Make sure to give the campaign ample time to send. For example, if the campaign is set to stop 24 hours after it starts, the email should probably be sent as a one-time email.
  • Weekdays: Select the desired days of the week when the emails will be sent.
  • Delivery Window: Enter the time of day when the emails will be sent. Select at least TWO delivery windows to ensure that the mailing is delivered as intended. It is important to note that when delivery windows are set on a mailing, Slate will pick up the messages once during this time range, and queue them to send any time within that time range.


Slate will only check once during that delivery window time frame to send out the mailing. The time in which it checks the mailing depends on where it falls in the queue of processes taking place during that window, and cannot be more granularly set. ​We recommend selecting at least two delivery windows for any ongoing mailing to be sure messages are delivered even in the rare event that it is not picked up during the initial delivery window. 

If a mailing should only be sent to a certain number of recipients in each delivery window, the Batch Size setting can be used. When a value is provided for Batch Size, Slate limits the number of rows pulled by the recipient list query or queries in each delivery window, and the mailing will maintain its status of "Scheduled/Running." When the next delivery window hits, the mailing will send the next batch of messages.

Additional Considerations


Emails and texts are never sent or delivered to recipients when messages are "sent" in Test, Clean Slate, or Time Warp environments, though they will appear on records' Timelines as if they were delivered. However, scheduled ongoing mailings do not automatically run in these environments, so they will not appear as if they were sent. Test ongoing mailings in a Production environment with test records to ensure that these mailings send as expected.

Click here to learn more about the differences in Slate feature behavior between test and production environments.

Running a mailing indefinitely is not compatible with Recipient Lists that are spreadsheets. If you want an ongoing, indefinite mailing, you must build a Recipient List through a query.

Additional settings include:

  • Batch Size (optional): A batch size can be included when limiting the number of recipients for a message. For example, if 10 is entered as the batch size, the mailing will stop after sending to 10 random records from recipient lists.
  • Review: Indicates that message is ready for review.
  • Outbox: Send to Outbox and do not deliver automatically.
  • Deduping: Used to denote whether a mailing should be sent multiple times per recipient, or only once. Refer to the Deduping section later in this article for additional information.
  • Delay Delivery: Delay delivery until a specific time. Note: If the recipient has an active address, Slate will use the time zone for that recipient. Otherwise, Slate will use the Eastern Time zone. Slate will also record the delay delivery time as the time the mailing was "delivered."

Deduping Settings

When setting the deduping selection, ongoing campaigns offer three options. Note that deduping takes place based on email address. Consider the following when deciding which option to select:

Deduping Option Description
Do not dedupe messages

The mailing will send to a record if:

  • The record satisfies the filter criteria
  • The record does not already exist in a query run for the mailing

Even if the email address for a record already exists as the recipient of the same mailing, the record with that email address will receive the message again.

If multiple records included in the same query run contain the same email address, all records satisfying the filter criteria will still be considered for sending.

Note: For mailings that use an uploaded spreadsheet for the recipient list, the original spreadsheet must be re-uploaded to re-send to the original recipients.

Send only one message/recipient

The mailing will send to a record if:

  • The record satisfies the filter criteria.
  • The record does not already exist in a query run for the mailing.
  • The email address of the record was not already used as the recipient for the mailing.

If multiple records exist with the same email address in a query run, only one message will be sent per email address. Other records with that email address will be skipped when the mailing is sent.

If a record that contains the same email address as a separate record that has already received the mailing is included in a query run, this recipient will be skipped and the mailing will not be delivered a second time to that email address.

Allow recurring delivery of this message to the same recipient

Selecting this option will allow the message to be sent to a record multiple times. When this setting is selected, previous query runs in the mailing will automatically be removed from the mailing each time the mailing runs. A frequency must be selected, defining how often this message should send to the same record (such as 1 day, 2 days,  or 30 days).


The mailing will continue to send to a record if:

  • The record satisfies the filter criteria.
  • Either the mailing has not been sent to the record, or the previous message was sent to the record at least x days ago, where x is the specified frequency.
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