Please, note! You can only send from one email address unless your device can store login credentials for multiple Microsoft 365 or Office 365 mailboxes. Office 365 also has a cap of 500separate recipients for each individual mail, as well as a cap of 30outgoing messages per minute.
To help stay below the usage limit, place frequent mail recipients into a static or dynamic distribution group. Messages sent to distribution groups only count as a single email, regardless of how many members the group has. If you need to send out frequent bulk messages to a variety of people, but want to keep your existing mail system for regular emailing, you can subscribe to an external bulk mail service to send messages on your behalf.