Here are examples of mailto links you can use:
mailto:nobody@notesinjas.com
mailto:nobody@notesninjas.com,zero@notesninjas.com
mailto:nobody@notesinjas.com,zero@notesninjas.com?subject=To%20Nobody%20and%20zero
mailto:nobody@notesninjas.com,zero@notesninjas.com?cc=cc@notesninjas.com?subject=To%20Nobody%20and%20zero,cc
mailto:nobody@notesninjas.co?bcc=bcc@notesninjas.com?subject=To%20Nobody%20and%20bcc
mailto:nobody@notesninjas.co?bcc=bcc@notesninjas.com?subject=useful...?body=check%20this%20%0Ahttp://www.notesninjas.com
The mailto link cannot be more than 256 characters, so don't overstretch.
If you wrap the line in an <a href="mailto..." you don't need to specify %20 for spaces.
You don't have to put in an exact email address, you can put in a group name if you wish like:
mailto:friends?subject=cool
Another bonus of having Lotus Notes set as your default mail client is you can right click on files in windows explorer and send them to a mail recipient, this creates a memo with the file attached.
This functionality works even if Lotus Notes is not yet open. Notes is opened and the password is requested. If you have single sign on enabled for the machine and Lotus Notes, you don't need to enter your password.
Domino Web Access (ie the web mail client for lotus notes) for version 6.5 can also be set up to be the default mail client, go to preferences->other in DWA to find the "Make default client" button.
To change your default mail client, in ie go to Tools->Internet Options->Programs and change Email.
Doing it in Firefox is trickier, see: http://kb.mozillazine.org/Default_mail_client#Setting_Firefox.27s_email_client
There is an executable here that adds Lotus Notes to the default email client in windows:
http://www.bluestream.org/Domino/LotusMail.htm Use this if Lotus Notes isn't an option already in ie.