In order to connect your team's Office 365 / Exchange Online environment with Charlie, you'll need to create a "mail flow rule" in the Exchange Admin Center (note that you'll need access to an account with administrator access to set this up):
In your Exchange Admin Center...
Go to mail flow > rules.
Click the + icon and select Create a new rule… from the drop-down menu.
Enter "BCC Route to Charlie" as the name of the rule.
Modify the criteria of the rule to apply to the relevant scenarios (You can simply choose [Apply to all messages], or set up some combination of criteria to target only the mail you want in Charlie.
In the "Do the following..." section of the rule, select "Bcc the message to..." and enter {YOUR_TEAM_BCC_EMAIL}@charlie.io in the box beside "Check names". Click the Check names button to apply the change, before clicking OK.
Save your changes!
Testing Your Connection
To test that your connection is working correctly, simply send an email from any email address in your domain to an external address. If the routing rule has been set up correctly, you should see the email appear in Charlie in a matter of moments!
If you're having trouble getting it set up, feel free to contact support!