In some cases, Exchange Online sends messages using TNEF (Transport Neutral Encapsulation Format). This typically occurs when Exchange assumes the message will be processed by another Exchange environment—for example, when a tenant sends messages internally (to itself).
Because TNEF is a proprietary format, Xink ReRouter ignores such messages by default.
To address this, the Xink TNEF message handler unpacks TNEF-encoded messages and converts them into the standard MIME format. Once converted, the message goes through the regular signature injection process and is returned to Office 365 in MIME format.
This process is seamless for end users—there’s no visible difference in how the message appears. However, Exchange Online administrators should know this background conversion and understand its role in appropriately applying signatures.
Note: Server-side settings are cached within the email processing farm. It may take some time before configuration changes are fully applied.
IT Pro: Handling Signatures for Internal Emails
