Thanks both of you, I checked everywhere (aside of mxtoolbox) for blacklists and all my IPs are clean.
A client was using email server to send mails to google groups and others list, with a LOT of rejected mailboxs (I received lots of rejected address, really lots, 2000+ per hour)... I didn't find any message in logs, and with yahoo right now mails are starting to arrive at inbox... cannot say the same for gmail, I still arrive to spam after this, before I was arriving always to inbox...
But well, I think that in a while it will be fixed without intervention of my side... if someone has more ideas please post here.
Regards and thanks again for your help and future advises!