This thread is reserved for mail sent to the covenant.
Your magi are often busy. Even when you get to see your sodali for dinner in the main hall, you might not have the time to have the important conversation you really want, to say things the way you really want, with the words that give your thoughts their appropriate gravitas.
Fortunately, you are literate! There is always sufficient time to compose your thoughts and set quill to paper.
By Hermetic tradition, a Quaesitor cannot view correspondence of this kind except in situations where he can use InMe against you. This stuff is kept in a secure covenant vault, difficult to get to. And woe betide the magus who betrays his covenant by removing any such writings! The world is not large enough for him to hide from angry magi who will dispatch him to the traitor's hell where he belongs.
So feel free to have those long conversations. Hold forth at length. Even when you are in the middle of nowhere, feel free to write at length, as long as you do not discuss your current adventure, or anyone else's.
Every word is IC, though 'translated' from Hermetic Latin into modern English.
NB: Many PbPs bog down or feel contrived because conversations either begin to look like speeches or letters, or each email has only a sentence or two. Sometimes characters who are not even there find ways to suddenly join interesting conversations. Now, your magi can communicate as they were meant to, via correspondence!