Implications of Microsoft Exchange Online limits to LMS365 email notifications

Organizations with many users of their LMS365 solution may face issues with the delivery of email notifications when sending them to many recipients within a shorter timeframe. These issues are due to Microsoft Exchange Online sending limits.

In this article, we describe these limits and what implications they have for LMS365 email notifications.


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Microsoft Exchange Online sending limits

Microsoft Exchange Online sending limits puts restrictions on the possible number of recipients (recipient rate limit), the number of messages, and the number of recipients per message that a user can send messages to from their Exchange Online account.



The Microsoft Exchange Online limits apply to both internal and external recipients.


The Microsoft Exchange Online sending limits include three restrictions:

1. The recipient rate limit limits the number of recipients a user can send messages to from their Exchange Online account per day. This limit is 10,000 recipients per day for LMS365 and is applied per user to all outbound and internal messages. After the recipient rate limit is reached, messages can't be sent from the mailbox until the number of recipients that were sent messages to in the past 24 hours drops below the limit.

For example, if a user sends an email message to 5,000 recipients at 09:00 AM, then sends another message to 2,500 recipients at 10:00 AM, and then sends another message to 2,500 recipients at 11:00 AM—hitting the limit of 10,000 messages—the user won't be able to send messages again until 09:00 AM the next day.

2. The recipient limit limits the number of total recipients allowed in the To:, Cc:, and Bcc: fields for a single email message. By default, the maximum number of email addresses that are allowed in the To, Cc, and Bcc fields is 500 in total, but Office 365 tenant admins can raise this limit to 1,000.

3. The message rate limit determines how many messages a user can send from their Exchange Online account within a specified period of time. For LMS365, the message rate limit is 30 messages per minute. If a user submits messages at a rate that exceeds the limit via SMTP client submission, the messages will be rejected, and the client will need to retry.

Find more information on Microsoft Exchange Online receiving and sending limits in Microsoft's documentation.


Implications for LMS365 email notifications

When LMS365 sends out email notifications, the system uses a connected Microsoft Exchange Online account. This account will be the sender of notifications. If outgoing email notifications exceed any of the limits mentioned above, these email notifications will be blocked from being sent.

This can happen, for example, if session invitations are sent to many recipients, exceeding the recipient limit, or if many email notifications are sent the same day, hereby, exceeding the recipient rate limit and the message rate limit.

If these limits will have an impact on your organization, contact the LMS365 Support Team to get help to work around the issue.


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