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How to integrate external e-mail accounts

Note: The features mentioned in this article are available in all packages except the Light package.

To set up external e-mail addresses to send

You can also use to send with external addresses that are not hosted by us. Please note the following:

If a very restrictive SPF record is set for the sending domain, there may be problems with the delivery of e-mails sent this way.
More information can be found at this article (in German): SPF / DKIM-Vortrag by P. Heinlein.

To set up sending via an external address, please do the following:

Click on the gear wheel at the top right. The "settings" are now open.

Select " - Alternative Sender". Enter your external e-mail address under (3) and select "Send activation link".

You will receive an activation link by e-mail. For security reasons, this link has a time limit and must be used within 15 minutes - otherwise it expires.

Now you can use your external e-mail address as sender in our web frontend.

Of course you can also integrate your external mailboxes via IMAP at This allows sending and receiving with these email addresses.
In this case you may not use the above method "Alternative sender" for the external e-mail address.
The problem mentioned above with SPF does not exist with this variant.

How to integrate external accounts via IMAP/SMTP

Go directly to your e-mail account and click on "Add email account".

Enter your username and password in the following dialog. All other settings should be recognized automatically. If everything worked out, you will now see your external account under your folders on the left.

Some providers need some additional adjustments in their preferences

We will demonstrate this with the example Google Gmail

  1. Please log into your Gmail account

  2. Choose Settings by clicking on the small gear and then on Settings

3.Please choose Forwarding and POP/IMAP

  1. Please enable IMAP by clicking on Enable IMAP under Status: IMAP is disabled and save these settings

  2. Now please log into your Google account (not your Gmail account!) and click on Security

  3. Scroll down and under Less secure app access please click on Turn on access

  1. A new window will appear. Under Less secure app access click on the switch to activate less secure apps.

  1. Now it reads Allow less secure apps: ON

  2. If you use Google 2-step-verification, you should set up a set up an app password.

You can do so by clicking on "Google Account", then "Security" on the left. On the right click on "App Passwords".
The name for the platform may be chosen freely. The type of service would be "e-mail".

Congratulations! You have now set up Gmail as an external account in your

Please note that accounts included like this will not be synchronized if you set up your mailbox on external devices.