One month and a half after the first one, a second company chose to sponsor my newsletter "le Courrier du hacker" https://lecourrierduhacker.com/ , a weekly digest of the Free and Open Source Software News in the French-speaking community.
A few days after reaching 2,400 subscribers, I seize this opportunity to communicate. I think it is related because I started to include in my different communications that I was looking for sponsors. And this is the second times that my sponsors tell me that he contacted me because someone (a subscriber I guess) told him I was looking for a sponsor.
So it's not just a coincidence anymore, seems like a business-model :D Only kidding but it seems I found both my sponsors telling my subscribers I was looking for sponsors.
The first sponsor paid for 3 weeks and this one wanted to test if the sponsorship was beneficial for him on one week.