This change is something that Blackbaud is aware of and will not have any impact on payment processing.  No action is needed by you as a client for this change.  The full text of the email from iATS is below:
 

This is a reminder of the November 2015 communication regarding certificate and cryptographic upgrades.

On February 3rd, 2016 at 12AM PST, iATS Payments will be removing protocol support for TLS v1.0 and upgrading to a SHA256 SSL certificate on www.iatspayments.com.  To avoid any interruption in processing, you will need to confirm your environment supports SHA256 and TLS v1.1 or v1.2. 

Please confirm your platform can handshake with the new standards before February 3rd. This can be validated using staging.iatspayments.com.

In case of an issue: A back-up URL www2.iatspayments.com with support for TLS v1.0 and SHA1 can be used. This is a temporary solution allowing you to continue doing business as usual until your systems support SHA256, TLS v1.1, v1.2.

It is important that you communicate with us via email at partners@iatspayments.com so we can troubleshoot and assist you moving to the updated production server.

To access the complete details regarding this upgrade, please click here