How to select menus in Mail.app using Apple Script - email

Question

What I'm trying to do is set up a smart Mailbox that will take a list of companies mailboxes that I'm assigned per day (ranges anywhere between 8 to 30 depending on the size of the account and the number of people working) so I can watch and assist the companies. Ideally what the script would do is accept a list of companies and then go through the mailboxes and add them to the smart mailbox like "Messages in mailbox" "Company A" but company A is in Mailbox > Letter > Company. Here is what I have so far.
set CustomerNames to {"Example, A"}
set CustomerNumber to 1
display dialog "What are the Customer's Names?" default answer ""
set CustomerNames to text returned of result
tell application "Mail" to activate
tell application "System Events"
tell process "Mail"
tell menu bar 1
tell menu bar item "Mailbox"
tell menu "Mailbox"
click menu item "New Smart Mailbox…"
end tell
end tell
end tell
end tell
keystroke "w" using shift down
keystroke "orklist2"
keystroke tab
keystroke "a"
delay 2
keystroke tab
key code 31 using control down -- Down Arrow
delay 2
tell process "Mail"
get the name of front Mail window
get the name of the selected menu
click menu item "Message is in mailbox"
keystroke tab
set the popupbutton to "CustomerNames"
click menu item "add criterion"
end tell
end tell
tell application "System Events"
repeat with CustomerNames from 1 to count of CustomerNames
click menu item "add criterion"
set the popupbutton to menu 13
set CustomerNumber to CustomerNames add 1
end repeat
keystroke return
end tell