It looks like you are setting up your installation of JESSIE to use the WHEEZY repository. Is that intentional? I'm not sure what the technical differences are, but it seems that might lead to problems.
>echo "deb http://download.mono-project.com/repo/debian wheezy main" | sudo tee /etc/apt/sources.list.d/mono-xamarin.list
>sudo apt-get update
Also, I thought you were having a problem with certificates. But, since you never install them it must have been something else going on. This is how I install certificates for yahoo mail:
7) Set up SSL certificates
sudo apt-get install mono-complete
sudo apt-get dist-upgrade
sudo certmgr -ssl smtps://smtp.mail.yahoo.com:465
confirm setup:
echo "" | openssl s_client -tls1 -showcerts -connect smtp.mail.yahoo.com:465
*** yahoo and most likely google require an app specific password ***
With wheezy, there was a different package that also needed to be installed but this should work for Jessie. If it worked, that echo command will show you a list of valid certificates from yahoo. But, if your method works, great!