Initial call was done by their recruiter, lovely lady, very nice and professional.
If it goes well, you go onto a 2nd round interview with a support manager, also was a pleasure chatting. Here you can ask a few more technical questions and learn a bit more in depth about what Paubox is (of course learn about them on your own time).
Then if that went well enough, you'll go onto final interview, where you'll speak with the support manager again and 3 other people (all back to back to back to back). The other 3 peeps were HR, and then 2 senior level technical employees. They were all great, kind, knowledgeable, etc...
You may be a finalist at this stage, but there's likely a good number of other final applicants as well.
I would also say at this stage the people who should be asking the best technical questions (the technical employees, people who you would be working with) asked some of the worst.
It's not their fault, but know that you will have to fight to keep the conversation on your relevant experience/skills (software, application setup/configuration/troubleshooting, email experience if you have any), and do not get bogged down by vague open ended questions that could derail into good but potentially detrimental conversation (ex: they might not care at all about complicated hardware experience for an email support position, even if that experience is impressive or was impactful at a previous role).
I have no problem with "what superpower would you have" questions, but if you're still battling to get the position, I think that's a waste of time and hurtful to the candidate (I know it's for how you would fit apart of the team). Questions by the most technical employees should have been focused on Office 365 suite, Gmail suite, networking, or application support/configuration experience. Specifics that are more relevant to the position.