I found the following article and was semi-successful.
https://stackideas.com/forums/change-text-sent-in-emails#reply-292185.
Specifically, I am trying to override COM_EASYBLOG_NOTIFICATION_SUBSCRIBE_SITE with a much longer letter and an embedded link for a download to say thanks for subscribing. My other overrides worked, but this override is blank in the email (not in the Languages Overrides". Is there a limit to the number of characters or some other reason that this part is blank? I know the above person also commented that it would be nice to have a way to change these email messages in an easier fashion, and I have to agree. I added html tags for line breaks <br /> and <a href> for the link to the download. Thanks for your help.