This is happening because your browser doesnt trust the MWG's CA. See below Best Practice on the matter:
This also seems like you do not have full Content Inspection enabled, more likley just "Set Client Context" as per:
Here is the master list of Best Practices as well:
activating the SSL (Create Client Context) Rule is always a good idea to show the user a blockpage if any SSL site is blocked. :-)
With our customers we did it in this way.
1) one customer exported the CA from MWG and deployed the CA certificate to all endpoints using Microsoft Group Policy.
2) If there is a PKI in place generate a subordinary CA and import this certificate to MWG.
jscholte, i remember to webwashere where donwloading the CA directly from the blockpage was available. Is this still available with MWG?
@MBM, in this case I'm guessing Haaris does not have full SSL scanning on (only Set Client Content -- so that block pages can be displayed for HTTPS sites). As such, he may not want to allow the site, or perhaps he does.
@Thorsten, as of 7.5.1 you can now host a certificate (.crt, or .cer) in the block templates folder, and subsequently link to it on the block page. Previously you could, however it would not download properly (display as just text).
Thank you very much for your support,I have imported the SSL certificate in my browser and it seems the problem is solved......