“to inform you…” is a kind of improper tone for the customer

我今早出了封電郵通知客戶公司將同事的客戶交由我交進，我用英文寫，其中開頭一句是
I would like to take this opportunity to inform you that I have been assigned to serve your company in the immediate future.

但同事指責用 "to inform you"是不適當，不禮貌，是否這麼嚴重呢？以下是句子是同事給我的一句
Also, “to inform you…” is a kind of improper tone for the customer, try to have a more polite why to express yourself.

請高手指教。