The prefix for proper is pro
Use the prefix of Mrs. if it is a fomal letter. If not, and you are familiar with them, use their first name.
It is improper.
what is the proper way to address the mayor
Proper
impure
the proper way to address the Queen is by "your majesty" or Ma'm, pronounced like "ham'
A hyphen is used to separate a prefix from a proper noun or adjective, especially when the combination could be confusing or misleading without it.
Ms.
The prefix "im" is a variant of the prefix "in". It creates the opposite of the original word. Examples are: moveable / immovable; possible / impossible.
The proper way to address the conductor of a symphony orchestra is 'Maestro.'
The proper prefix would be "Ms." "Miss" is for unmarried women. "Mrs." is used for married women. "Ms." is used when marital status is unknown or when the woman does not disclose it intentionally.