Use of imparfait

Question

In this week's writing challenge we had ".. I've received a letter from your company. It notified me that .."  ->  "J'ai reçu une lettre de votre compagnie. Elle m'informait que ..."    How can we know that this is better than  " Elle m'a informé que ..."

Accepted Answer

Bonjour Joakim !

Another interesting question!
In this context, the use of L'imparfait will be more colloquial than Le Passé Composé.
In this sentence, it's like you're considering the process of reading the letter, during which the letter *was informing* you:
"J'ai lu ta lettre. Dedans tu me racontais tes vacances."
(I've read your letter. In it you were telling me about your holiday.)

Using Le Passé Composé here oddly creates the impression that there was no intent of informing in the letter, like you being informed was a fortuitous consequence of reading the letter rather than the purpose of it.
It's like the use of two tenses creates a link between the situations, when 2 Passé Composé feel like these situations were put next to each other with no "link" in-between them (i.e. I received your letter and it informed me.).

I hope that's helpful!
À bientôt !