Global exclude filter

[DeniR]

Need global exclude filter.
I have some important emails, that never will be deleted. I want to exclude it from duplicate search across all mailboxes.

[eyalroz]

Do you need to keep duplicate copies of your important emails?

I've not gotten such a request before.

[DeniR]

I have important emails with same subject across all mailboxes and subfolders, so I don't want to delete it. No I even can't deselect them, coz there is no mass select/deselect in group, only by click on each mail, but I have more 100 important mail.
I use 'subject' as duplicate criteria.

[eyalroz]

... and do you usually compare messages by subject only? An additional comparison criteria would likely solve this problem.

[DeniR]

I have a lot newsletter with same subject in all mailboxes, and important mail with non-unique subject.
As I say before, I can't use extension fully, while it can't process all mailboxes. Also there is no way to select/deselect all found duplicated mail in group, so i can't fast exclude important mail group.

[eyalroz]

I'm sorry for the very long delay in replying.

So, let's talk about what such a filter would look like. Supposedly, for each comparison criterion, I would need... a substring or regular expression to match, such that messages matching it are never reported as dupes?