My team and I have created a list to collect all hard bounces categorized as "unknown user."
We use this list to requalify contacts, as this category generally indicates incorrect email addresses.
However, we’ve noticed that some contacts with whom we exchange emails daily have also been added to this list under the "unknown user" hard bounce category.
After investigation, it appears that the hard bounce was caused by a marketing email that exceeded the maximum size allowed by their server.
This type of issue doesn’t really fall under the "unknown user" category.
Would it be possible to create a separate category for such cases?