Thank you both for your input. I did also notice that I could produce the certificate window with the "Install Certificate" option via Internet Explorer but unfortunately this gets a little messy when you get to Internet Explorer 10.
At the client where I was trying to install this system they had various versions of Internet Explorer on the PC's and laptops and I found in some instances in Internet Explorer 10 the PC may produce a message at the bottom of the screen "Intranet settings are turned off by default" and if I clicked on the option "Turn on Intranet settings" I could produce the window with the "Install Certificate" option. But this Intranet settings message did not appear on all Internet Explorer 10 PC's so it got a bit hard and I think I will need to somehow import the certificate to each PC or laptop via a file.
I also noticed (and the documentation at
http://wiki.contribs.org/Email_-_Setting_up_E-mail_clients_for_SME_8.0 also mentioned it) that the certificate has an expiry date in my instance of July 2014. I'm not surely going to have to visit all of the users again in 12 months time to effect this again!
I also noticed on one Windows XP PC which can successfully access the server manager of a version 6 SME system via Internet Explorer that when I try to access the server manager of the version 8 system Internet Explorer responds with "The page cannot be displayed" suggesting that there is some sort of DNS error but the same PC can browse the iBays OK. I did try logging on to the PC via a couple of other user names and got the same result. So getting the certificate on this PC via Internet Explorer also didn't work.
Is there any way around this email configuration issue to perhaps make it a more simple task like it has been with version 6 for instance?