Would smart mailboxes work for you?
A Smart Mailbox displays a set of email messages, stored in other mailboxes, that match specific criteria you have defined. For example, you might create a Smart Mailbox that searches all your mailboxes for messages from a specific sender and displays them. Smart Mailboxes are a fast and convenient way to group together and display messages from various locations, without having to physically move the messages between mailboxes.
You can create Smart Mailboxes that search for matching messages in a single mailbox, a group of mailboxes, or all mailboxes. Smart Mailboxes automatically update the list of messages to include new messages that match the criteria you defined.
When you make a change to a message viewed through a Smart Mailbox, such as marking the message as read or unread, or moving or deleting the message, the change is reflected in the mailbox where the message is actually stored.
Choose Mailbox > New Smart Mailbox.
Use the pop-up menus and text fields to define the search criteria for the mailbox. If necessary, click the Add (+) button to expand the search criteria.
You can also create a Smart Mailbox by using the search field in the top-right corner of the viewer window and then clicking the Save button below the search field.
To change the search criteria or to rename a Smart Mailbox, choose Mailbox > Edit Smart Mailbox. To delete a Smart Mailbox, select the mailbox and choose Mailbox > Delete.
Creating a Smart Mailbox folder
You can use Smart Mailbox folders to organize any Smart Mailboxes you have created. For example, you might create a Smart Mailbox folder named "Travel" and then drag and drop into it three Smart Mailboxes you created to organize email from three travel vendors.
To create a Smart Mailbox folder:
Choose Mailbox > New Smart Mailbox Folder.
Type the name of the folder and click OK.
As with regular mailboxes, you can "nest" Smart Mailbox folders by creating new Smart Mailbox folders within existing Smart Mailbox folders.