Useful commands to allow port in iptables, delete port in iptables, save iptables permanently.
Grant Mailbox Access Permission to Microsoft365 Mailbox
To grant full access to an Microsoft 365 Mailbox you must first connect to the remote PowerShell, and provide MailboxPermission.
PowerShell Connect to Exchange Online
Steps to connect to Exchange Online in Microsoft 365
PowerShell connect to Microsoft 365 AD
How to install Microsoft 365 AD PowerShell modules, both AzureAD and Msol and how to connect to Microsoft365 PowerShell