There is no option to approve selfsigned certs in Evolution Exchange connector.
To replicate
On first run of Evolution -> Selecting Server Type as Microsoft exchange and
using the url of https://x.y.com/exchange - to an exchange server using a self
signed certificate.
Pressing authenticate brings up the dialogue to enter the password.
Clicking OK just returns to the Receiving email dialogue.
The username and password (pasted from clipboard) work in firefox after
accepting the self signed cert.
I opened a ticket with Ximian some time ago on this. Here's what they say
"Here's what we think is the problem. If this is a "self signed" certificate
and it is just one level then there are many programs that will fail because it
is not truely a "Trusted Host". The certificate should be signed by a trusted
host such as Equifax or at least there needs to be another layer, not just one.
Web browsers don't seem to care. They will let you accept the cert anyway.
This certificate signing is a configuration on the OWA/IIS server."
I can confirm this issue. I even downloaded and added my company's certificates
to evolution's certificate store.
It's still broken. This was working fine until my company turned off
non-encrypted owa, and I can access owa just fine using a web browser.