I might be a stupid question but is their a mass email clean up tool with eM?
There is a very handy utility in eM Client called Deduplicator (Menu > Tools > Deduplicator) This will go through your folders and remove any duplicates in Contacts, Emails etc. You can specify either specific folders, or the whole lot at once, and then have the option to verify each one before deleting them.
If this is not what you are looking for, can you give more details about what you want to clean up?
I would like this as well. I have over 30000 messages in my inbox (had it for many years) and I would like to be able to see some useful stats so that I can target email deletions. For example, if I see that 10% of my emails are from a mail list, I can delete them and unsubscribe. At the moment, I have to randomly manually scroll through my emails and find groups of emails to delete.
Any stats that would highlight largest senders, disk space, date last message sent,unread etc would be really useful to enable me to control my mailbox.