As part of the Email Relay integration with Trustifi, you will be required to make some changes to the "Remote domains" section in Exchange.
These changes are domain-wide, and affect the way emails are sent by default from your Exchange environment.
This article will explain in depth what these changes mean and why they are required.
Disabling Rich-Text Format (RTF)
Rich Text Format (RTF) is a legacy proprietary email format that Microsoft created before HTML emails were popular. RTF was used before HTML to apply styles on bullets, align text, add links to objects (pictures/etc.), add icons and more.
Microsoft has since deprecated RTF in favor of HTML; "You can use RTF when you send messages inside an organization that uses Microsoft Exchange, but we recommend that you use the HTML format. In fact, when you send an RTF message to someone outside your organization, Outlook automatically converts it to HTML, so the message keeps its formatting and its attachments."
Disabling RTF during the Email Relay integration acts to make sure emails will not be sent with Rich Text Formatting, so that all of the visual elements of regular and encrypted emails will be delivered correctly.
Changing the character set
Changing the “MIME character set” to “Unicode (UTF-8)” is meant to minimize the number of possible problems with message encoding (e.g. "?" instead of Cyrillic symbols), we recommend to set up a unified, universal encoding in Exchange to UTF-8.
UTF-8 is recommended for everyone who uses national characters found in many European alphabets, so that and if the client’s Windows is set to a different charset, it will make sure all content is aligned to UTF-8.
Support "Out of Office" (OOF) external and legacy replies
Out-of-Office (OoF) is used for automatic replies, automatic forwarding and for other types of features used by OoF such as Microsoft Teams and other products by Microsoft.
The change from “Allow only external Out of Office replies” to “Allow external and legacy Out of Office replies” is to mainly support Outlook 2003 or earlier clients or emails sent by Exchange 2003 or earlier servers with Trustifi.
This setting change also solves some feature-issues with Microsoft Teams such as calendar invites when sent internally; since there’s now a connector to Trustifi, and without the OoF change for “legacy”, Exchange doesn’t deliver all of the invite information and parameters to Trustifi, as it's handled as an internal email (even though it goes out to Trustifi)