Encrypt Multiple Documents with Macro

[userr]

Hello,

I have a spreadsheet which contains:
First Name
Surname
Email
Encryption Key

I need to create an individual letter for each person on the list, which
includes their name and details. I then need to encrypt (Password Protect)
each
letter with the password that appears in the "Encryption Key" field.
This letter has to then get attached to a mail, and sent to that persons email.
Could someone please help with this. I have approx 500 people on the
spreadsheet.

PS: Googling for this seems like it can be done. The only thing I cant seem to
find, is a way to get each file individually encrypted with the password on the
"Encryption Key" field.

Thanks in advance