I have several imap accounts and want to click one button to empty all junk mail at once. How can I do this?

Question

I currently run Apple Mail on Lion with several IMAP acocunts... I know that there is a right-click option to remove "all deleted" messages  but what If I wanted to do the same for all messages marked at junk in all accounts.  It's really a pain to have to click on each account, select all the junk in the junk folder, press delete over and over.. and then right-click and select "Erase Deleted Items"    Why the heck can't they just have "Erase All Spam Items" also... ??   Or how about "Erase all SPAM and DELETED ITEMS from ALL accounts"   ????

Answer 1

I found the solution and here's how to correct things:
Apple Mail
Mail has a feature, accessible from the Mailbox Behaviors (or Special Mailboxes) tab of the Accounts preferences, that can automatically delete old spam messages from the Junk mailbox. You can use this feature if you tell SpamSieve to put spam messages in the Junk mailbox instead of the Spam mailbox.
(Note: If you do this, be careful not to use the Junk and Not Junk buttons that will appear in Mail when the Junk mailbox is active; you should always use the SpamSieve - Train as Good and SpamSieve - Train as Spam commands instead. You can use the Customize Toolbar… command in Mail’s View menu to remove the Junk button from the toolbar. Also, if you select a message that SpamSieve has classified as spam, Mail will show a banner saying that you marked it as junk. Ignore this.)
Make sure that Mail knows which mailbox is your Junk mailbox by selecting it and choosing Mailbox ‣ Use This Mailbox For ‣ Junk.
To tell SpamSieve to use the Junk mailbox, open Mail’s Preferences window and click on Junk Mail. Make sure that Enable junk mail filtering is checked. Select Move it to the Junk mailbox. If Mail asks whether you want to move all the messages to the Junk mailbox, say No. Next, select Perform custom actions. Then click theAdvanced… button and edit the rule such that the conditions don’t match any messages. For example, use these two conditions:
Message is addressed to my Full Name
Message is not addressed to my Full Name
and set it to If all of the following conditions are met. Click OK to close the sheet. Do not make any further changes to the Junk Mail preferences.
Go to the Rules section of Mail’s preferences and change the SpamSieve rule to move the messages to the Junk mailbox instead of the Spam mailbox. Finally, chooseSpamSieve - Change Settings from Mail’s Message menu and, when prompted, say that the name of your spam mailbox is Junk.