Submitted by Our Languages blog on July 12, 2021, at 16:19
Dear Pat,
If you don’t know the person, you can use their first name or initials, followed by their last name. Here are some examples taken from our recommendation on gender-inclusive writing in correspondence (https://www.noslangues-ourlanguages.gc.ca/en/writing-tips-plus/gender-in...):
Dear P. T. Smith:
Dear Amrita Kumar:
In a salutation, you would never use a pronoun (for example “them”), because you're addressing the person directly.
We hope this answers your question.