sending mass e-mail – only want them to see data revelant to them

I have an excel list of usernames and passwords. I was wondering if there was a way to automate the following process:
Send each person an e-mail with only their username and password. I don’t want to attach the excel list as it contains passwords for everyone.

Someone suggested I could set each person up as a contact and somewhere on the New Contact screen type each users name and password. Then create a distribution list from the contacts. I tried this but it did not work.

Is there an easy way to automate this or do I need to type an e-mail to each person and give them their username and password?

Thanks in advance