Here are some examples of expressions to avoid:
- Attached herewith…
- This is to advise you…
- As per your request…
There are simple, elegant, plain English alternatives which are perfectly polite.
- I have attached (or enclosed)…
- I’m writing to let you know… (in some cases you don’t even need this.)
- As requested…
I think my favourite of use of antiquated expressions of all time was in a letter I once received that finished with the words:
“I remain, Sir, your obedient servant.”
I felt I had time-travelled to the 19th century.