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IP whitelisting for business customers

IP whitelisting allows's business customers to restrict access to their managed mailboxes by permitting access only through predefined networks. Any access attempts made from outside these specified network areas are systematically blocked. This enables the configuration of mailboxes in such a way that secure access is guaranteed exclusively through the corporate network. Accordingly, a VPN connection is required for access outside these networks. Thus, IP whitelisting provides an additional layer of security against unauthorized access. Setting it up is easy and ready in minutes.

Details at a glance:

  • Access to email mailboxes is only possible through predefined networks.
  • The restrictions apply to the login via the website and access via IMAP (for example access via Outlook or other mail clients).
  • Maximum flexibility through individual configuration of each mailbox.
  • Set up multiple IP addresses as comma-separated list.
  • Compatible with the IP standards IPv4 and IPv6.


  • IP addresses belonging to a private address space (for example, or can not be used. Read more about private networks on Wikipedia.
  • Access to CalDAV, CardDAV, and WebDAV is not affected by this settings.

How to set up IP whitelisting for a mailbox

To define a network or a list of networks for a mailbox, follow these simple steps:

  • Log in to your administration dashboard at
  • Click on the domain whose mailboxes you want to configure.
  • Click the edit button (1) of the mailbox or e-mail address you want to configure.

  • Scroll down at the menu that has opened at the right side and enter or paste a comma separated list of your IP-addresses (IPv4 & IPv6) in the field "Allowed Nets" (2).
  • Confirm your input by clicking "Save" (3) (figure1).

That's it. The IP whitelist is active for this mailbox and access is now restricted to these networks. Repeat the process for any other mailbox if desired.

Figure 1: Add your desired IP adresses and hit save to confirm your input.