Sending extremely large numbers of emails is very complicated. This post will attempt to explain the sending process as well as explain some of the many considerations that have to be made while sending every email.
Using the Queue tab
A new tab has been added to Email+. The Queue tab displays exactly what Email+ is doing at any given time. The queue can be viewed from many different perspectives, which will help you determine where your email is in the queue and how quickly it might complete sending. The queue can be viewed:
- By Server - displays the number of emails in the queue waiting to be sent by each server. Email+ has five servers that send emails; each server's total and the grand total are listed.
- By Provider - displays the providers in the queue and how many emails are being sent to each. The table also displays the per-minute limit for each provider, which is the max limit under ideal conditions. Often the actual number of emails that can be delivered per minute is lower than the max.
- By Priority - displays each email by subject and where it falls in the queue according to priority. The table is sorted by priority (high, medium, or low) and the sent date/time.
When is the best time to send large emails?
Currently a large email is defined as one having more than 25,000 receipient addresses. Large emails are sent at a lower priority than small emails. If you send large emails during the work day, you run the risk of others doing the same. On Tuesday five large emails were sending at the same time: four of the emails were sent to about 55,000 people, and one of the emails was sent to 300,000 people. It took 12 hours to process all of these emails. Smaller emails, which are set to a higher priority, were still able to send during this time.
The best time to send large emails is in the early morning hours. Any time after midnight is ideal. This will not only get your email out quickly but will lighten the load on the queues for everyone else during working hours.
What happens when an email is sent using Email+?
- Each email address is marked as ‘campus’ or ‘non-campus’. Campus addresses are emails like lance@illinois.edu, bob@uic.edu, jill@uis.edu, tim@uillinois.edu, etc.
- Campus addresses are sent to a set of email relays managed by Tech Services.
- Non-campus addresses are sent by our Webtools application servers directly to email providers like gmail.com, yahoo.com, etc.
- Each email is assigned a priority based on the number of addresses to which it is being sent. Higher-priority emails contain less than 5,000 addresses. Medium-priority emails contain between 5,000 and 25,000 emails. Lower-priority emails contain more than 25,000 recipient addresses. This is done so that large emails that take many hours to send do not tie up the queues for everyone else.
- The system retrieves the preferred providers list which determines the max number of emails that can be sent to any provider in one minute. Examples of providers are gmail.com, illinois.edu, uic.edu, yahoo.com, etc.
- The system sorts all addresses by priority and submitted time.
- The system reads through the sorted list of emails and sends what is allowed per minute by each provider. Once the list is read through the process begins again.
Emails Per Minute (Limits) by Provider
Emails are throttled down to per-minute limits for each provider, else they are identified as spam or deferred. The numbers below are the maximum number of emails that can be sent to that provider in one minute.
| illinois.edu |
150 |
| uic.edu |
150 |
| uis.edu |
50 |
| uillinois.edu |
150 |
| gmail.com |
250 |
| aol.com |
250 |
| comcast.com |
250 |
| comcast.net |
75 |
| hotmail.com |
250 |
| msn.com |
250 |
| sbcglobal.net |
250 |
| yahoo.com |
250 |
| all others |
25 |