intermittent issues with proxy server error (80000000) in Outlook 2010. SSL Offloading on LTM.

In the end after a lot of tcp dumping and reproducing, F5 support claims it is a regression on the client side (Microsoft). They have an article describing it:

K10433354: TLS handshakes from some clients may intermittently fail when using Diffie-Hellman ciphers

Since we have support for better ciphers than those with problems, we decided to create a new SSL client profile and assign it to the VIP for MSX. This is our ciphers list in that profile:

DEFAULT:!EDH:!DH:!DHE:!RSA:@STRENGTH

After that we have had no more problems with those errors. Hope it helps.