You can have up to 8 "verified" email addresses associated with your PayPal Account. Note, to associate an email address with your PayPal Account, it must be "verified". One of those 8 verified email addresses must be selected as the Primary Account email address. If you are manually coding your item button code, then you can use any of the 8 verified email addresses as the "business" variable value in your item button code. What ever address you use is the one the email notification will be sent to. If you are using the online button creator to generate either "hosted" or "encrypted" item button code, then by default, the online button creator will you your Primary Account email address. This behavior is by design cannot be changed unless you change the Primary Account email address.
Tip: If manually coding your item button code, the "business" variable line will look similar to the example below, you would simply change the value to email address of your choice.
<input type="hidden" name="business" value="youremail@youremail.com">
Regards,
skier
