Messrs. Smith and Jones
Messrs. Smith
Messieurs Smith and Jones
Messieurs Smith
You could write "Dear Sirs and Madam" in a business letter, or you could write "Dear Friends" in an informal letter.
men
Messrs. Smith and Jones Messrs. Smith or Messieurs Smith and Jones Messieurs Smith
Dear Sirs,
Gentlemen and Madams
Use all four names or find some phrase that covers them like: Mr J. Doe and family.
Gentlemen, ...
send two letters :)
There are two addresses in a business letter. If letterhead is used, that acts as the 'return address' of the sender; if letterhead is not used, the sender's address must be at the top of the letter. Then there is always an 'inside address', the name and/or address of the person or entity that the letter is sent to.
The two letter suffix used to designate a Spain internet address is es.
Letter for one person with two addresses
"Gentlemen.............rtc" for more than one man if your addressing them