Agenda email confirmation Are you planning to attend this meeting? YES NO

Hi. I looked at the documentation and couldn't find an answer to this. 

When getting an Agenda sign up email, and clicking NO, sometimes it opens an email for me to send back. Other times, It opens the browser for me to login and confirm that I will not attend. Why is the same NO button behaving differently? 
"Are you planning to attend this meeting? YES NO" 

My preference is to not have to logon to confirm.
Any help is appreciated:)

See the section titled 'Use MAILTO Links in Agenda Emails' in this document;

support.toastmastersclubs.org/doc/item/member-profile

Thank you, Richard! Do you know if the default setting is checked or unchecked?

Unchecked. It's disabled by default because some email clients do not properly handle MAILTO links.

Make sense. Thank you for your quick reply.