Is it possible to protect 2 or 3 or … computer with avast home edition for example i have 3 computer and avast is on internet computer the other are connected by lan can i protect mail for all computer ?
First of all, Flashback, WELCOME to forums ! Stay here and we’ll allways find some solution. You’ll find best bunch of people in here, and whenever you need help, there will always be someone ready to help.
Regarding your question, I’m not 100% sure, but I think and I’m 99,9% sure that you can’t do that with Home Edition. You have to purchase Server Edition. See here:
http://www.avast.com/eng/purchase/network_solutions/index.html
Or, if you’re “short” on money, why not installing avast! Home Edition on all computers in your little private network ? It’s very easy and very functional. I have two machines, one is running Professional Edition (Thanks Alwil, I’m thankful till I die), and another one is protected with Home Edition. Both of my PCs are connected through my 4 port router/firewall.
Hope this clears that little bit…
Cheers !
Is this small network at your home or at your office?
At my home
There is a way, but it is rather complicated and I don’t advise it for a small homenetwork.
Easier is installing Avast on all systems or if you have a server os on the system that takes care of the connection use the server edition of Avast.
As far I tested it, you can update avast through the Internet if the connection is shared with the other computers.
If not, you can manually download the vspupd.exe file on the webpage and apply to the off-computers 
Oh, I forgot, you can use the same registration number for the three computers