How to access an Office 365 shared mailbox on Android?
Shared mailboxes on Exchange Online don’t have their own logon, but connection is possible for any user with Full Permissions using IMAP or POP3 access.
You should use the following settings on any Android Device:
E-mail: shared-mailbox (example: info@company.com)
Username: primary-mailbox\shared-mailbox (example: info@company.com\dragan.todorovic@company.com)
Password: primary-mailbox-password
Server name: outlook.office365.com
Port: 993
Encryption method: SSL
Server name: smtp.office365.com
Port: 587
Encryption method: TLS