S/MIME support on mobile devices is “must be” feature for our big customer (to continue to use IBM Traveler)…
K. Reeves presented during Connect 2014 (session 102 - Innovations and Priorities…) this feature as priority for Traveler in 2014, but I was not able to find any release schedule with S/MIME support… Dou you know more on this topic?
Subject: Unfortunately, S/MIME is not supported…
It’s just about Notes native security - look into your links:
…
- Only Domino-encrypted mail is supported. Encrypted calendar, to-do, and notebook entries are not supported. SMIME encryption is unavailable.
…
Subject: companion app
You can do secure messaging with you have ID installed into the mail file and have to appropriate companion app for traveler on your phone see
http://www-10.lotus.com/ldd/dominowiki.nsf/dx/Traveler_Companion_FAQ http://www-10.lotus.com/ldd/dominowiki.nsf/dx/Traveler_Companion_FAQ
Subject: Thanks for tips, however we need to solve Blackberry 10 resp. Android devices…
… that don’t use Traveler Companion 
But i can confirm your tip for iOS/Companion devices, S/MIME works there.