You put in your address and instead of saying "Dear sir," you would say, "To whom it may concern"
Gentlemen and Madams
men
Dear Sirs,
Gentlemen, ...
There are several types of vice admirals and you would address them as such. For example you would address a rear vice admiral in a letter as Dear Rear Admiral.
If you are addressing several men and women in a letter, then the salutation can be 'Dear Ladies and Gentlemen'. Another salutation can be 'Sirs and Madams'. These types of salutations can be used for men and women that are on a committee.
You could write "Dear Sirs and Madam" in a business letter, or you could write "Dear Friends" in an informal letter.
Messrs. Smith and Jones Messrs. Smith Messieurs Smith and Jones Messieurs Smith
There are several kinds of abbots, depending on their duties and assignments. You can follow the link below, to decide which kind of abbot you want to address, and then choose the proper address to use.
The return address on a letter is the address of the person sending the letter. It is important for the recipient of the letter to know from whom and where the letter originated and to have an address to respond, if necessary.
Messrs. Smith and Jones Messrs. Smith or Messieurs Smith and Jones Messieurs Smith
Letter address