About a year ago I added some info about this little add-on for thunderbird calle Merge Email. I then described how-to use the address-book to make merged emails. Since I am a bit of a fan of this add-on I'll describe using it with a csv-file.
Mozilla Thunderbird have quite a few good extensions. One of them is MailMerge. This extension allows for using Thunderbird to send personalized emails. Of course there are some rules you need to obey to for this to work. But here is a quick how-to for sending personalized emails to a group of friends or colleagues.
