I guess you are a MobileIron engineer, and that you won’t come back to check my replies.
Regarding this particular point I’m really looking for a clear feedback from MobileIron that I didn’t get before.

Our reseller sold android support this way :
* We cannot configure android native mail app because android API do not support it
* We offer you a better alternative, for free ( Namely, touchdown for MobileIron )

But things have not been that nice in the real world. We are using lotus Traveler and facing the following limitations :
* NO free email client supporting activesync ( Even less supported by mobileIron )
* TouchDown had huge limitations in Traveler support ( No meeting invite support, no embedded images, messy HTML support …)
* Free Touchdown version was removed from the market.

Now, what would you advise for supporting our Android users to have a nice MobileIron Experience ?

This is not an Android limitation. Nothing prevents MobileIron from allowing Android devices to get to the traveler server (it could simply tunnel the HTTP(S) connections through) but MI have chosen not to follow that route.

Alpha 3 is out ! Should work much better, give it a try.

Please also try this :
Settings > Applications > Devel > Device Hostname
And change it to something below 8 char like “MyTP”.

Good luck !