What do you think about me sending my ex from 15 years ago a text message?
That's really random, why did you message her after all those years?
I broke up with her in 2006 and she didn't have internet accessibility until very recently.
I know you wanted to reconnect with your ex, but she may not want you to contact her. It's best to avoid opening up old wounds and not contact your ex. She may not welcome your attempts to try to reconnect with her.
Relationships fade thus the need to contact her comes back. I'm going to type a message for her soon.
I don't see the harm in contacting an ex if the messages are welcomed, however if she gives you the impression that she does not want to rekindle the relationship you should stop.