Following security best practices and industry-wide changes, Salesforce will be updating all HTTPS security certificates to new certificates with a SHA-256 hash algorithm.

We are asking all customers to be prepared for this change by:
April 1, 2015 for Sandboxes
August 1, 2015 for all Instances

We will begin changing certificates in a phased approach shortly after these dates. Exact dates will be provided in March 2015.

There is a chattergroup for customers to interact with us to ask us questions here:
https://success.salesforce.com/_ui/core/chatter/groups/GroupProfilePage?g=0F9300000001oAF

For more information, see this Knowledge Article:
https://help.salesforce.com/apex/HTViewSolution?urlname=HTTPS-Security-Certificate-Switch-from-SHA-1-to-SHA-256-hash-algorithms&language=en_US (https://help.salesforce.com/apex/HTViewSolution?urlname=HTTPS-Security-Certificate-Switch-from-SHA-1-to-SHA-256-hash-algorithms&language=en_US)

Hi,

Because of SSLv3 Poodle vulnerability, we have turned off SSLv3 support on our web server. This in term is causing Salesforce outbound messaging to fail.

Is there a work around with this from Salesforce end?

The outbound messaging processing issue was resolved once we turn SSLv3 back on our web server.

Ted Tsung