Limitations with Microsoft 365:


Microsoft 365 Mailbox Staff Only

Mailbox storage limit50GB
Message size limit20MB
Attachment limitWith individual attachments limited to 20 MB
Subject length limit255 characters
Recipient rate limit10,000 recipients per day.
After the limit has been reached, messages can’t be sent from the mailbox until the number of recipients that were sent messages in the past 24 hours drops below the limit.
Recipient limit400 recipients, distribution group counted as one.
Message rate limit30 messages per minute
Retention period for items removed from the Deleted Items folder14 days
Maximum message size for large distribution groups (>5000 members)2 MB



Microsoft 365 OneDrive

OneDrive (sharepoint included) storage5TB
File and path lengthUp to 400 characters
File upload Limit250 GB per file
Invalid file typesFiles with a *.tmp or *.ds_store extension, desktop.ini, thumbs.db, or ehthumbs.db (Full list of file type cannot be added)
Any file that’s currently open by an application.
Invalid characters in filename/folder" * : < > ? / \ |
No. of Items (files & folders) can be synced to OneDriveUp to 300,000 files


For more information, you can refer to the following links: