The simplest solution is to just share them with us in the support ticket. Our web interface is secure so you don't have to worry about your server credentials being leaked.
You are free to change the credentials after we are done assisting you if that works with your security policy.
If you are uncomfortable leaving that info available in a past ticket (we can't erase them), there are web services available for providing one-time, password-protected links to your sensitive text. Below are just a few of the options.