I would really love to add an additional option to perform on filtered emails:
add a [SPAM] tag to the subject line on emails that match the filters.

Rather than auto-deleting flagged messages, a [SPAM] tag enables the client to sort the incoming emails. False positives would be on the email client itself instead of the MW trash bin thus making it a true Set-And-Forget program as you would never need to access it other than to tweak filters and lists.

One of the biggest problems is that users do not know when a false positive occurs. Its only after a couple of days passing do they realize that something is amiss or worse, they receive a phone call from an angry agent demanding a reason for being ignored. Then they have to hunt down the email admin (who may be on vacation) to go check the spam bin for them.

So please add just one more option under the Delete, Bounce, Automatically section: Add [SPAM] tag to subject line.
Thanks!

After rescuing an email from the greylist, it is delivered to my inbox. However, as soon as it enters the greylist, a reject response was sent to the originating server. Assuming that it is a valid email (and it should be, that's why you rescued it), the server will try again within 15 mins. When the second (and duplicate) email arrives, as it was rescued, it arrives directly to your inbox. Mailwasher should discard this second email as you already have a copy.

Add to Whitelist/Blacklist from Tracking
Would be really usefull to be able to add email address to Whilelist/Blacklist from the Tracking screen by means of a tick box or double clicking the message

If a message has been blocked, it would be helpful to be able to view a preview (larger that is currently available through the tool tip) of the message before I click on rescue.

If I (or somebody else) rescues a message by mistake, there should be an option to be able to undo the rule created by rescuing the message so that similar messages do not get though the filter in the future.