Not sure what "lMail" is, perhaps a tie_po?!
My advice is to
never respond to any SPAM, even to "unsubscribe". I assume you have some rules in Mail telling it to mark emails with certain criteria as "SPAM". Or perhaps you are using SpamSieve? At any rate, both Mail and SS have settings letting you tell them what to do with SPAM. I generally tell them to dump it in either "Trash" or another mailbox like "SPAM". That way, you never see it in your Inbox. I then "empty" the trash occasionally after verifying there are no 'false positives'.
Any response you make to a SPAMmer marks your email address as not only active but that you will actually read their garbage. What proof do you have that convinces you that they would really "un-subscribe" you from their lists?! By responding, you actually make your addy more valuable and will surely add yours to their lists they usually offer for sale to other SPAMmers. Most of the actual SPAM senders don't really have web sites that consider the wishes of their "customers" anyway. The "un-subscribe" link probably goes to a domain that the SPAMmers highjacked to look authentic and that hacked company will have no idea who you are. Besides, they didn't send the email anyway.
If you are using SpamSieve, absolutely, positively always use the Message->SpamSieve - Train as Spam menu to tell it you want it to treat an email as SPAM. The key word there is "Train", SS can get better if you keep training it.
will [Anti virus apps] take care of virus without opening mail?
AV apps
running on your computer look through your email files on your drives to spot virus. So you still have to open Mail and let it download any messages on the servers. Some ISPs will do that searching while the emails are still on their servers, before you ever see them.
Fortunately, I can't remember ever getting any notice that there have ever been any emails containing malware that would run on a Mac. What I sometimes see is that ClamXAV has found a file on my drive that it thinks is possibly dangerous or that has characteristics of malware matching things in its database. BTW, most of those come from Adobe products...
Actually, there
are dumb questions, just search here for numerous examples from me!
But the more you visit
and post, the sooner you earn points to erase them!!
Which reminds me, how is your post hole business doing? It's been several years since I needed any but I tend to buy them locally to save shipping costs.