I don't know anything about "cron", but I may be able to help you:
How do you have the employee's birthdays, in a database? In a text file?
also, what format do you have the birthday data,
Which format is it listed:
January 2
1/2
1-2
If in a database, do you have the month and date in separate fields?
say you have the data like 1/2
this is like:
print date("n/j");
so, maybe you write some code to check your database (or file) for a row
where today's date equals the date of the employees bday, then you set an exact time on the date and when that date and time are reached, mail an email to those with the day's date birthday
confusing,
well it's an idea, email if you
sammy