Yes, current email blaster tools allow you to customize the content sent to subsections of your followers. This is done through list segmentation which makes a sub-section or sub-list of your mailing list based on a certain criteria. For example, if you have a mailing list containing people from all over the world but want to alert just those in New York City about an upcoming protest, you can segment your mailing list based on their city and send a message only to those in New York City.

This list segmentation feature, however, presupposes that you have the information that you want to segment by. If you only have a person's name and email but don't have their city you won't be able to include them in segments based on location. This is a big caveat because many times people won't proffer more than the bare minimum of information (their email address).

However, if you do have additional information that you can use for segmentation, it opens up many doors for interacting with your email constituents. You can, for example, try out two different subject lines and see which segment provides a greater open rate. Or you can send a Spanish translated newsletter to your constituents in Chile while a French version goes to the segment of your list that is located in France. Just remember to be mindful about not leaving out information to a segment that they may in fact be interested in.