The phrase "which informed you" is grammatically correct and commonly used in written English.
Example: The article, which informed you about the new government policies, was published in today's newspaper.
Our management team and Board were disappointed that even our latest outreach, which informed you of our intention to present you with a revised, increased proposal if we were to meet, was rejected without a meeting.
Somewhere very prominent – I might be wrong in imagining it was the front page – it used to carry a Court Circular which informed you not just of the comings and goings of royal personages and their footmen, but the visits of unsuitable foreign dignitaries and the wild doings of debutantes.
Result: Go Compare, Compare the Meerkat, confused.com, etc etc etc. Prediction: "Constant video feeds of your house will become common, which inform you when somebody visits while you are not home".
Imagine, if you will, Richard Nixon without the vision which informed his better moments.
I contacted Pure, which informed me it must be a hardware fault.
The recall was initiated by Great Southern, which informed the Food and Drug Administration.
With the exception of occasional paid announcements which informed an interested public that "K.O".
"I was more pessimistic as an adolescent in the late 1970s and early 1980s, which informed my work.
Everitt called his Edinburgh office, which informed the Metropolitan Police, in London.
An African-American student there, Henry Thacker Burleigh, introduced Dvorak to spirituals, which informed his American works.
It was this which informed his critique of ideologies of purity and his recognition of the dangers that they posed.
