Organizations that have a large number of LMS365 users may face issues when delivering email notifications to many recipients within a short timeframe. These issues are caused by sending limitations in Microsoft Exchange Online.
In this article, we describe these limits and their implications on sending LMS365 email notifications.
In this article:
Microsoft Exchange Online sending limits
Microsoft Exchange Online sending limits put restrictions on the number of recipients (recipient rate limit), the number of messages, and the number of recipients per message that a user can send from their Exchange Online account.
Microsoft Exchange Online limits apply to both internal and external recipients.
The Microsoft Exchange Online sending limits consist of three restrictions:
1. The recipient rate limit. This limits the number of recipients to whom a user can send messages from their Exchange Online account per day. This limit is 10,000 recipients per day for LMS365 and is applied on a per user basis 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 who were sent messages in the past 24 hours drops below the limit.
For example, if a user sends an email to 5,000 recipients at 09:00 AM, then sends another message to 2,500 recipients at 10:00 AM, and 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. This limits the number of recipients who can be added to the To:, Cc:, and Bcc: of an email message. By default, the maximum number of email addresses that can be added is 500 but Office 365 tenant admins can raise this limit to 1,000.
3. The message rate limit. This 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.
Implications of these limits on LMS365 email notifications
When LMS365 sends 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 previously in this article, they won't be sent.
This can happen, for example, if session invitations are sent to a number of recipients that exceeds the recipient limit, or if a lot of email notifications are sent the same day, thereby exceeding the recipient rate limit and the message rate limit.
If these limits are likely to impact your organization, contact the LMS365 Support Team to get help on how to work around this issue.