After all these years I finally fell prey to having my Mac invaded by this intruder. I ran an AVAST scan and it displayed the culprit and so I deleted it. However, soon after it re-appeared. What I now want to know is there an AVAST program that will eradicate these intrusions for once and for all ? Thanks everyone.
Banff: this is Avast! forum for windows only, please repost ur questions in Avast! forum for Mac here (http://forum.avast.com/index.php?board=5.0)
i shall answer the general question though, there is no antivirus programmes which will completely protect u from all kinds of intrusions/malware attack on both windows and Mac platforms. eg, norton, Avast, kaspersky…so on.
just have an antivirus programme, firewall and use the web safely 
Thank you for your reply. I kept at it and finally came across a posting that explained how to amend the settings in your mail program preferences. I experienced a problem at first in being unable to come up with the ‘Advanced’ setting for the Incoming Mail Server because clicking on the ‘+’ sign did not seem to work, but I eventually managed to insert it and since then there has been no repeat of the intermittent annoyance. Chalk another one up for AVAST.
I had to make a point of submitting this for all concerned. Immediately on pressing the ‘Post’ button to send the previous comment above re: apparent resolving the matter of the SSLs/TLSs, not one but five altogether, one after another collectively of the SSL connection notice appeared on my iMac’s screen. So evidently the proposed changes that I had implemented do NOT work. The immediate reaction to sending the posting was truly alarming, for this is getting quite serious as I am beginning to get the notion that my privacy is being violated and I am seriously considering informing the police. I’d be more than happy to receive comments from the AVAST community on whether they have had similar experiences and what they did to put a stop to it.
please post in the Mac forum for Avast! only. yesterday was the weekends, so u can expect them to reply today/tomorrow.
please be patient.
+1
And in case you need the link: http://forum.avast.com/index.php?board=5.0
Thank you both, you’re very kind. Don’t know why I keep ending up in a PC forum. I’ll now check before I post.