Wish him / her a 'Happy Birthday'
 

Wish Andrew a 'Happy Birthday' for me:

• Felicita a Andrés por su cumpleños.
• Dile a Andrés Feliz Cumpleaños de mi parte.

Are the above two translations correct?
I'm not sure about the use of 'por' in the first one.
Are there any other ways to express the same idea?

Many thanks in advance.

OK in a combined form: "felicita a Andrés de mi parte por su cumpleaños"

give him my regards:

dale mis saludos
dile que le envío saludos
dale saludos de mi parte

This last use is usually more formal, but it's often used to disambiguate, like in the sentence you're asking about, as "felicita a Andrés por su cumpleaños" means primarily "don't forget (yourself) to say happy birthday to Andy"

Many thanks, aleCcowaN.