|You can do it using Microsoft Word (I know it's not freeware but it may be what you are already using) - under the 'mailings' section there is Mail Merge and one of the options under that is email - a simple wizard walks you through it. A couple of provisos though, you need Outlook (I don't think it will work with Outlook Express, though I may be wrong on that one) and the art of getting it right is to have your data file (with the names in) correctly set up in the first place - the wizard will help you with that part though.|
As far as replies are concerned, the easiest way is to just put a link to the other person's email address and ask that replies are sent by clicking on that.
EDIT: I've just checked and if you don't have Word then OpenOffice, which is free, also has the same facility - under Tools/Mail Merge - when you are asked 'type of document', email is the second option. As far as the Outlook alternative you may want to look at Thunderbird - I've never used it but its proponents regard it as being better than Outlook so I should hope it can do the job.
"I've always been mad, I know I've been mad, like the most of us..." Pink Floyd