[tushartyagi]

Assuming the mails are still online with the mail provider, I think that copying that data on local disk, indexing and then running queries on it should work. Doing this locally will save time and then you can sync back the changes.

I know of two tools which might help.

One that I use is more Emacs oriented. My personal setup uses mu4e[1], fetches emails using mbsync, indexes the emails using mu and allows you to run queries based on date/time/subject/content etc. You can quickly search, mark, delete and archive emails.

The other option would be to use a similar combination of notmuch, offlineimap and mutt[2]. I have used mutt but with the online services (i.e. without downloading my emails locally), so I am not sure how that will work. But mutt also support similar tagging and searching and running operations on selected emails.

Caveat: Make sure you have enough understanding with what you do with these tools, they also have the capacity to delete all your emails on cloud. Perhaps run the queries on some test emails first.

[1]http://www.djcbsoftware.nl/code/mu/mu4e/

[2]stevelosh.com/blog/2012/10/the-homely-mutt/