Can I clean duplicate EML files without deleting replies from the same email thread?

[ivyclarkharris]

My backup has many emails with the same subject because they are part of long client conversations. I do not want a cleanup process to remove valid replies by mistake. I need to remove only exact duplicate EML messages while keeping full conversation history safe.

 

[ashishseono]

Yes, but do not clean them by subject line only. Replies in the same thread may share a similar subject but they are not always duplicate emails.
Keep a backup first, then use a duplicate checker that reads email details properly. GainTools EML Duplicate Remover is a practical offline tool for this purpose because it works with EML/EMLX files and helps remove real duplicates while keeping attachments, message properties, and folder structure safe. Test one thread heavy folder in the demo before cleaning the full archive.