Are there limits to the size or number of messages I can send?

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A single message sent from Microsoft 365 can have a maximum of 500 recipients.

Why am I receiving emails from @microsoft.com addresses?

Microsoft occasionally uses email to inform users about service features and license information. While it's important to exercise caution with email claiming to be from a trusted source, it's also important to empower yourself with the knowledge and common sense required to determine if a message is legitimate or illegitimate.

The Microsoft 365 team strongly encourages everyone to familiarize themselves with phishing concepts and review available resources on how to protect yourself from phishing. Another great starting point is the UT Austin Information Security Office guide on how to detect a phishing email.