WiscList (Advanced) - Throttling Mailings

The following procedure details the process by which list administrators may throttle mailings. Throttling is a rate-limiting procedure that releases a mailing to small subsets of a WiscList over a period of time.

WARNING: This procedure is not without risk and must be performed in strict adherence to this guide. Failure to follow the procedure correctly can result in problems with your mailing, including large amounts of duplicated messages. If you have questions, please contact the DoIT Help Desk.

Why should I use throttling?

  • Ensures timely delivery of your mailing once it has been sent.
  • Mitigates problems on your web server(s) resulting from people clicking links in your mailing.
  • Minimizes impact on campus infrastructure including critical alerts, academic communications, and normal day-to-day operations.

When should I use throttling?

While the number of members is not a strict indicator for when to throttle messages, we generally see performance issues with lists containing over 30,000 email addresses. You should consider throttling your message if it meets any of the following conditions and your list exceeds 30,000 members:

  • Your message is being sent during normal business hours.
  • You include an attachment or are close to the 5MB message size limit.
  • Your message directs users to click on a link or hosted resource.

Any list that exceeds 30,000 members should almost always have messages throttled; if you have questions or would like to request an exception, please contact the DoIT Help Desk. For additional considerations, information, and guidelines for large mailings, please see Mass Email - Best Practices.

What are the risks?

Failure to perform this procedure correctly will result in duplicated mailings, something that should be avoided whenever possible. You may also fail to send the mailing to everyone on the list, so it is important to follow the procedure closely, and to seek assistance whenever uncertain.

How do I get help with this?

For assistance with this procedure, please contact the DoIT Help Desk. An agent will assist with the procedure or escalate a case to the WiscList team for further review if needed. If you have an urgent need, please indicate this to the Help Desk agent so that WiscList staff are made aware.

Procedure: Throttling Mailings

Throttling Guideline

When throttling messages, a best practice is to release no more than 10,000 messages every 30 minutes. Content must be created in List Manager as this procedure is not supported for messages originating in an email client.

Create Content in List Manager

  1. Log into the WiscList Advanced (List Manager) interface; please see WiscList - Advanced List Management (List Manager).
  2. Create the content that you wish to send in your mailing using the Content Editor. See the following for assistance with the Content Editor: WiscList - Using the Content Editor in List Manager.
  3. Once you are satisfied for your content, click Create Mailing to begin assembling the message.

Create the First Mailing

  1. On the New Mailing screen, set the desired parameters including Mailing name, From, To, and Subject. You will also see a copy of the message in the HTML and/or Text sections.
  2. Click the Recipients tab. At this point you should have a rough idea of how many messages you plan to break your mailing into.
  3. Since this is the first mailing, enter the number you plan to send during a single session into the Sample size box. In the example below, we choose to send 5,000 messages during the first mailing.

    Throttle sample size

  4. Once you've entered the Sample size, click the Schedule tab to choose when the first mailing will go out.
  5. Click the radio button next to schedule for and choose a time.

    Throttle schedule

  6. Click Save to schedule the first mailing, or Save and Test to have an optional test message sent to the address of your choosing.

Create Subsequent Mailings

  1. Repeat the procedure above to create a New Mailing and set the same parameters with the exception of the Mailing name which must be unique.
  2. Click the Recipients tab.
  3. Enter the same number as before in the Sample size field (e.g. 5,000 in the example below).
  4. Click Choose Mailings next to the Purge from row to remove the recipients from the first mailing.
  5. Select any mailings that you previously scheduled using this process and click >> to add them to the Chosen Scheduled Mailings to Purge From list.

    Throttle purge 1

    Throttle purge 2

  6. Click Ok to return to the Recipients tab.
  7. Click the Schedule tab to choose when the mailing will go out.
  8. Click the radio button next to schedule for and choose a time AFTER all of the previous mailings you've scheduled using this process. You must leave at least 30 minutes between mailings.
  9. Click Save to schedule the mailing, or Save and Test to have an optional test message sent to the address of your choosing.
  10. Repeat this process until you've accounted for all the members on your list (i.e. a list of 30,000 would have 6 mailings, assuming a 5,000 person sample size).


You may review your scheduled mailings in the Mailings : Scheduled screen in List Manager.

Throttle scheduled messages

When performed correctly, this procedure will choose a random subset of the sample size you specified for each mailing. Mailings are sent according the schedule you created in the steps above.

Note: You cannot edit the sample size or the purge list once the mailing has been scheduled. If you make a mistake, delete the mailing and begin where you left off after the last scheduled mailing.

Keywords:limit rate throttle schedule scheduled throttled release slow distribute distributed stagger   Doc ID:45688
Owner:Josh O.Group:WiscList
Created:2014-12-16 16:47 CSTUpdated:2017-05-15 10:47 CST
Sites:DoIT Help Desk, WiscList
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