guccounter=1 ?

Yahoo ?

think  it's on all email providers

"?guccounter=1"
Is this a virus or spyware?

Actually, it is due to you, being "BAD" on your Yahoo account.  I garnered it on my account when a troll who had around thirty accounts used them to thumb every one of his comments/posts up and everyone else's down, so I began making accounts and doing the same to him. :)  In any case, he had the audacity to report ME and then left me a comment that his kid worked at Yahoo and that I'd begin seeing a counter when I logged on, so that yahoo could see how many accounts I have (had).  LOL.  Well, to begin, I doubt Yahoo would need to use a "counter" to do that, but I do believe it is Yahoo who incorporates it on some accounts, and not a virus.  That said, unless you're doing something bad, nothing comes of it.  (Thumbing people up or down thirty+ times is apparently not frowned upon by Yahoo).

https://answers.microsoft.com/en-us/protect/forum/protect_other-protect_scanning-windows_7/is-guccounter1-a-virus-when-i-open-yahoo-mail/ab0dba18-d43e-406f-846f-28f57399def6

I already that and many other google links, they're all conflicting and nobody seems to have a clue.

Ask Terry McCann, he'll be able to tell you who is spying on you