If you decide to change the email address used for sending and receiving emails:
You will first need to disconnect the existing one, then connect the new one. Follow the steps in the link here on how to disconnect your existing email account.
Once this is done, you probably want to keep receiving all the replies to the old email address. This can be done by auto-forwarding your emails.
Enable Automatic External Forwarding for All Mailboxes
To access the Anti-spam policies in Microsoft 365 Defender, log in as a Microsoft 365 administrator and navigate to the "Email & collaboration" > "Policies & rules" > "Threat policies" > "Anti-spam policies." Alternatively, you can go directly to the Anti-spam settings page here
PLEASE NOTE! If you don't see the aforementioned options or if no policies are displayed on the page, it's likely that the Microsoft 365 user you used to log in does not have sufficient permissions to make changes. Make sure you're logging in as an administrator for your account. It's worth noting that the policies you see in your own admin may differ from those shown on the default policies page.
Click on the "Anti-spam outbound policy (Default)" option, and then scroll down the sidebar until you find the "Edit protection settings" link at the bottom.
Once you've clicked on that, locate the "Forwarding Rules" section and find the dropdown list labelled "Automatic Forwarding Rules."
Select "On - Forwarding is enabled" from the dropdown list
Click on "Save" at the bottom to save your changes.
Enable Automatic External Forwarding for Individual Mailboxes
To access the Anti-spam policies on Microsoft 365 Defender, log in as a Microsoft 365 administrator, and select the "Email & collaboration" > "Policies & rules" > "Threat policies" > "Anti-spam policies." Alternatively, you can directly visit the Anti-spam settings page at this link: **https://security.microsoft.com/antispam**.
2. Click on “+ Create policy” and select Outbound.
To create a new outbound spam filter policy, click on the "+ Create policy" button and select "Outbound."
Next, give your new policy a name and description.
After that, click "Next" and search for the user account that you want to allow to forward emails. This should be the email account that you're forwarding to Help Scout, and it will be displayed under the "Users" field after you select it.
Click "Next" again, and then scroll down to the "Forwarding rules" section.
Click on the dropdown list under "Automatic forwarding rules," and select "On - Forwarding is enabled."
Finally, review the settings on the last screen and click "Create" to create your new outbound policy for the specified user(s).