Formatting Issues When Logging Emails from Outlook.

Custom formatting in email content, like tabular structures, custom formatted pre-built Outlook signatures, and other formatted content inserted in the email body, can get distorted when the option "Log Email on Send" is enabled in the Salesforce Outlook Integration add-in.

Why This Happens

When the user toggles on Log on Send, Outlook Integration uses Office.js from Microsoft to obtain the email body being composed and adds a pixel URL into the body. This pixel is added to track the relation of the email to an ID in Salesforce like Lead, Account, or Contact.

When the editor is set to Rich Text mode, this Office.js API removes the table structure and formatting in the original signature. This means that even if what's returned from the API is inserted back into the email composer as-is, the signature format will change.