A: Hello,
Spam is a complex issue, you have to go step by step until you find the reason. in no case it is a problem of the tool, we confirm that it wotrks normally. If it is something punctual, it is very possible that in future shipments it will be solved even without changing anything. The most important step is the DKIM configuration, here is the article:

https://en.soporte.acumbamail.com/article/66-configurar-dkim-y-spf-para-tus-envios

Once you have this point, our next recommendation is that you review all the points that we put in this article and once you have done all of them, do new tests.

As a last note, remember that the big email managers focus fundamentally on the response of subscribers to your campaign, and based on this they send or not a spam campaign. For this reason, the quality and time of your list is key throughout this process.