Actually, if it's a mailing, it's not spam... but it is potentially
junk mail. The concepts are different, even if the activities
sometimes overlap.
Would you be offended to be called Mrs. Don Smith or Ms. Don Smith?
Chances are reasonable that you'd be offended to some degree. If not,
then don't worry about it. Otherwise, someone called Mr. Jane Smith
might be offended, resulting in them taking a dim view of your
advertising. If they are all doctors, the use "Dr.". If you're not
sure, you might have to find something neutral, but applicable.
The actual usage... create an extra column beside your existing column.
Put the formula in the first cell beside the first name. (Adjust it
from referencing A1 if the name isn't in A1). Copy the formula all the
way down. Highlight the whole column with the formulas. Edit -> Paste
Special ... -> Values. At this point you can delete the original
column.
Note: If you're not all that proficient with Excel, I'd recommend you
make a backup copy of your spreadsheet, so you can go back to it and
try again.
Scott