What you need to know about email sending limits at the University of Kentucky Refer to these do’s and don’ts when sending bulk email at UK

Whether you're sending a message to a few colleagues or a large campus audience, University of Kentucky Information Technology Services (UK ITS) wants to remind the campus community of sending limits and best practices for email usage at the University of Kentucky.

It’s especially important to understand Microsoft’s bulk email policy, which does not allow users to email more than 500 recipients in 24 hours.

Bulk email refers to sending a single email to a large number of recipients at once — like a newsletter. At UK, it is highly discouraged to send bulk email via M365 mailboxes.

Sending Limits

Microsoft 365 email accounts at UK have built-in limits to help protect against cybersecurity risks like spam and phishing. Here’s what to keep in mind:

• 24-hour sending limits: Outlook limits how many messages you can send in a 24-hour period. For most inboxes at UK, Outlook will not allow you to send to more than 500 recipients in 24 hours. This means that if you send one email to 200 recipients at 8 a.m., you could not send another email to 301 recipients at 10 a.m. Every recipient counts towards the 500 limit and is not based on unique recipients.  
• Shared Inboxes: For those that send emails from a shared inbox, the 500 send limit applies to the individual sending the email, not the shared email address.
• Calendar Invites: It is important to note that calendar invites sent from your Outlook inbox count towards your send limit.  

Need support? If you have a valid business reason why your Outlook inbox needs to exceed these limits, you can request an increase using the Exchange: Increase Recipient Sending Limit form. Increasing an Outlook inbox’s send limit should only be used in cases where a third-party bulk mail tool would not be appropriate.

Do’s: Bulk Email Best Practices

When sending bulk email, be sure to follow these best practices.

• Use approved tools: Avoid sending bulk messages directly from Outlook. Instead, use tools like distribution lists, Microsoft Teams or a Microsoft office group for mass communication explained here: Use these communication tools as alternatives to the UK Listserv service | Information Technology Services
• Departments have the option to purchase supported third-party bulk mailing services through their college. Contact your college’s business office for more information.  

Don’ts: What to Avoid When Sending Bulk Email

• Not following bulk email rule can result in your email account being locked for 24 hours.
• If you email more than 500 recipients, your email account will be locked.  

If you exceed the recipient limit, UK ITS cannot unlock your account. Microsoft sets Outlook sending limits, and once a limit is exceeded, you have to wait 24 hours before sending an email.  

Why Limits Matter

Bulk emailing limits help protect UK’s email systems from being flagged as spam. They also ensure deliverability, so your message reaches its audience.

Limits also help maintain trust with recipients by avoiding unwanted or excessive emails, and most importantly, they prevent compromised accounts from sending phishing emails in bulk sends.

To read more about Microsoft’s email limits, visit What are the sending and recipients limits for Microsoft 365 email?

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