I would suggest a number of points:

a) Have the user define a list of tags available in the main viewer window. Currently, the only way to apply a tag is to open an email and then manually click on the tag name. Use this list to tag the mail from the main viewer window.

b) Have the ability to bulk apply tags that is: select a group of messages and tag them all at once.

Please add this feature! It will be much appreciated.

I am currently using MailTags, but would much rather have Mailbutler support tags.

What if I say, this could be a deal breaker some.

This feature would be superb. To accomplish this currently (in Apple Mail), you must buy another third-party product called MailTags. Tag support in MailButler means one bolt-on product fewer.

Yes - yes - yes !