Hi Etienne
I checked the campaign you have with the 902 response and the issue is with your host blocking AWS IPs. I could not find any SSL or SNI errors for the domain.
You will want to reach out to your hosting provider to make sure they are not blocking any AWS IP ranges. Our IPs are dynamic so we will not be able to provide a range for you.
There are also other issues with the SSL configuration which will need to be looked at which could result in different errors once the IPs are unblocked.
http://www.screencast.com/t/b8qEdNah
You can run a test here for any SSL domain: https://globalsign.ssllabs.com/analyze.html
Hope this helps!