A delivery failure notification indicating that an email message could not be delivered to the intended recipient. This issue typically arises within Microsoft Exchange environments when attempting to forward messages to addresses that are still referenced using an outdated or incompatible format, specifically, the Exchange legacy format. An example of this would be an attempt to forward an email to a contact that retains an obsolete address entry within the Exchange system’s address book.
The problem often signals underlying issues related to address book synchronization, legacy system configurations, or incomplete migrations. Its resolution prevents communication breakdowns, ensures reliable email delivery, and maintains data integrity. Addressing this error allows for smoother transitions during server upgrades or organizational restructuring by removing dependencies on obsolete address formats. Understanding the reasons behind this specific failure aids in simplifying email administration and improving overall efficiency in email communication.
