Forwarding
E-mail forwarding is not always that easy. SPF records can be broken, and if an email is lost, it is not easy to debug where it got lost. We therefore recommend not to use e-mail forwarding whenever possible. If you still need a forwarding there are the following possibilities.
As Admin
You can create Sieve filters as an administrator or domain administrator.
Forwardings created by Sieve filters are ARC-signed and the envelope-from header is rewritten accordingly.
This way, there are fewer problems with SPF.
- Navigate to - /mailbox, then- Filter
- Add a new filter with the following content. 
Forward and delete:
redirect "user1@example.com";
discard;
Or forward and keep in the inbox:
redirect "user1@example.com";
keep;
Or you can also forward emails to multiple recipients:
redirect "user1@example.com";
redirect "user2@example.com";
discard;
Note
For creating a forwarding you can also create an alias. However, the envelope-from header will be kept, which may cause problems with SPF. In our case, Postfix  cannot perform SRS.
As Mailbox User
As a mailbox user you can create a forwarding within your webmail. Technically, this also use sieve filters.
With SOGo:
- Navigate to - /SOGo, then open settings
- Click on - Mail, then- Forward
- Create your forwarding here 
With Roundcube:
- Navigate to Roundcube, then open settings 
- Click on - Filter
- Create your forwarding rule here