2anser I've not had this experience so far.
Only after your comment I looked through reviews and found that some users mention they sometimes don't receive emails from trustworthy sources. On the other hand, the Infomaniak support writes that they use standard practices for filtering mails and that sometimes faulty filtering can happen - which happens for a lot of big email providers who use the same mechanisms, too
So, my opinion about this is, that I can continue to trust it.