Help! (again)

OK. I give up. I've tried for two days running, and I still can't work out a word in Lesson 65. It's in section 530, in the sentence that runs:
"When you use our lists, you have the assurance that your message is being delivered to those merchants throughout the country who are [SOMETHING] for your goods - and to nobody else."
It's mem-r. or Men-r. Or something like that. I've run out of ideas :-)

(by kevinwal for everyone)