Yep, you just have to add:
db domains setprop mail.mydomain.com RequireSSL yes
signal-event webapps-update
There's some other options for each domain (like proxypass, rewriterules, access restriction etc...), you can take a look at this template: /etc/e-smith/templates/etc/httpd/conf/httpd.conf/WebAppVirtualHost/50Content
Regards, Daniel