If you are planning to send a mass email campaign to a large number of recipients, please review Email: Send a Mass Email to see if any of our mass email solutions will suit your needs.

If you still wish to use your own mailbox or a resource mailbox to send to a large number of recipients, Information Services recommends taking the following measures to improve deliverability:

• Avoid large email blasts. Keep your recipient list under 500 recipients. For best results, use lists under 300 recipients per message sent.
• Ensure that your recipient lists are current and accurate. Sending emails to a large number of invalid recipients is one of the indicators of spam.
• Don’t send mail to users who didn't sign up to receive messages from you. These recipients might mark unwanted messages as spam. Let them know they may request to be removed from future mailings if they prefer.
• Keep the Subject brief but descriptive. The Subject should be a brief summary of what the message is about, and the message body should clearly and succinctly indicate what the offering, service, or announcement is about.
• Any links in the body of the message should be similar and consistent, and not varied.
• Avoid content with large images and attachments or messages that are solely composed of an image.