"Try" would be more common than "attempt" in this case (i.e. "I tried to send you two e-mails..."). This is a correct use of the word attempt, but it doesn't sound completely natural here for some reason. So, I would recommend that you use "tried" instead.
Since you are referring to two e-mails, you should say "but they didn't go through..." rather than "but it didn't go through..."
Also, I don't think you need the comma after "though".