If you received an email with content similar to the below:
On October 22, 2009 server upgrade will take place. Due to this the system may be offline for approximately half an hour.
The changes will concern security, reliability and performance of mail service and the system as a whole. For compatibility of your browsers and mail clients with upgraded server software you should run SSl certificates update procedure.
This procedure is quite simple. All you have to do is just to click the link provided, to save the patch file and then to run it from your computer location. That's all.
Thank you in advance for your attention to this matter and sorry for possible inconveniences.