mutt: configure index color based on To: header

Question

i access proton mail through mutt and i've added a custom domain that goes through the proton account. therefore my INBOX has incoming mail to 2 different addresses. i'd like to color (in the index screen) only those emails that are addressed to the custom account:

like this in muttrc:

color index none green default me@custom_domain.com

but it doesn't work. i have no problems coloring the line by setting the pattern to a specific From: address. like:

color index none green default myfriend@some_email.com works perfectly.

i can also set the pattern from the subject or body... but NOT the To: header. why is this and how do i change it?

(just to be clear: i am not trying to change the colors in the pager header section, but rather in the index itself)

Answer 1

figured it out. hope this helps someone later:

color index none green default '~C me@custom_domain.com'

didn't need the ~C for selecting from other fields. only for To:

this helps me see at a glance which of my accounts they were sending to.