blank emails with links

For a few months now I have been getting blank emails with links purportedly from people I have formally corresponded with. They come with other people in the "to" field, so it appears some malware has stolen the supposed sender's address book. I never click on the links, and I have never found any malware on my computer as a result of these emails. But how can I be sure when I cant find out for certain what causes it by searching the web? Is it some as yet unidentified malware? How can I (or the other victims) fix it when we dont know what causes it?

 

Wow, nobody knows anything about this even here? Or was I remiss in not mentioning I use Windows XP and Thunderbird. The accounts the emails came from (supposedly) were either yahoo.com or aol.com.

 

Those emails seem to be just spam.
Is there any reason to suspect you're getting these emails because of an infection?
Are the other names in the 'to' field in any way connected?
Are you sure it's from one address book or might they just be a selection of random names?

Probably some crawler has just collected/found your email address and it has ended up on a spam list.
As it isn't outright spam; for viagra or from a familymember of a recently deceased king of Africa, it might seem more suspicious.
Just don't click on those links, unless you want to check what kind of infection (probably bogus AV ransom ware), you might end up with.

If you want to scan your notebook for infections/for a second opinion, use both Malwarebytes'Antimalware and Hitmanpro3.
Check my sig for download links.

 

In each case, I can tell from the other "to" addresses that they were gleaned from the forged sender's address book. So some malware or malperson either stole their address book, or is sending the emails from their computer. There are no mysterious emails in my outbox, so it has apparently not infected mine. I spoke with one of the "senders' and they said they were nowhere near their computer when the email was sent. To me the most plausible explanation is something swiping addresses from people, then the person responsible uses them to send spam.
But how do they get the addresses in the first place? How do you/they protect against it?

This is apparently happened with Gmail a few times, and it was suggested the accounts were hacked. But hacking an account just to steal some addresses to send stupid links to seems like a huge waste of time, to me. So I suspect its malware doing it but I really no nothing about it. And apparently nobody else does either. Whatever is it is, it is spreading...and I want to know how I can protect myself and how my friends can clean their computers so I dont have to filter their emails out.