I created several mailboxes and now I’m not sure how to access it. Is there webmail available? Or should I access using IMAP / SMTP?
you can use both mentioned.
We offer a RoundCube webmail. You can also use any available e-mail client (Outlook, Thunderbird, Mail, etc.).
We have so far only Czech manuals for e-mail clients. You can have it translated with Google Translate.