In general, the size limit for a single message sent from a Microsoft 365 email account is 100 MB. This size limit includes all attachments. A single message sent from Microsoft 365 can have a maximum of 500 recipients. If you're expecting an email and don't see it in your inbox: If you find legitimate email in your Junk Email folder, we recommend doing the following: 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. Slow delivery of email originating from external sources is typically caused by a large demand on the Mail Filtering Service. If inbound emails are delayed, service administrators will address the issue to ensure prompt delivery of messages. Delays generally do not last longer than an hour. Mail between internal services take a separate path through the Mail Filtering Service and will be unaffected by inbound delays. An inbox full of unsorted, unmanaged emails can clog the system and slow down access to your messages. There are three things you can do to manage your email, whether you use Webmail or a desktop email program: clean, organize, and filter. Cleaning Delete what you won’t use — Stockpiling messages in your inbox slows you down in two ways; you spend time searching through large quantities of email and it makes the server work harder. Empty trash and spam folders — Many email programs keep emails you've deleted in the trash folder. This takes up space on your account, so remember to empty your trash regularly and delete the contents of your spam folder. Manage your sent-mail folder — If you automatically save copies of sent messages, remember to delete ones you don't need. Email conversations frequently include your original message. Archive old messages — If you want to archive old messages, create storage folders on your local computer and compress and save old emails there. Caution: Archiving messages to your local computer does not guarantee the preservation of your files. Make sure to regularly back up your hard drive to preserve your archived messages. Organizing Create and use folders — Create and use folders to sort and store information you want to keep. This not only helps organize your information so you can find things more quickly, but it also it helps your inbox stay at a manageable size. Download attachments — Since email attachments take up a lot of space, it's a good idea to save attachments to your local computer and then delete the message from your inbox. If you need to save both the email message and the attachment, save them both to your computer and delete them from the server. Unsubscribe from all those advertisements — When you purchase something online, you are often automatically signed up for that company's mailing list. In no time, you'll be getting dozens of unwanted advertisements per day. Each of them should have an unsubscribe link at the bottom — follow that link to remove yourself from those mailing lists. FilteringAre there limits to the size or number of messages I can send?
What do I do if I'm missing an email I'm expecting?
Why am I receiving emails from @microsoft.com addresses?
Why is email delivery slow?
Tips for Managing Your Inbox
