Update u_e-sogo.md

docs/u_e-sogo.md

@@ -7,3 +7,23 @@ As of December 21 2018 we removed our custom themes due to complains about missi
 ## Change Logo
 mailcow builds after 21 December 2018 can change SOGo's logo by replacing `data/conf/sogo/sogo-full.svg`.
 After you replaced said file you need to restart SOGo and Memcached containers by executing `docker-compose restart memcached-mailcow sogo-mailcow`.
+
+## Connect domains
+Domains are usually isolated from eachother.
+
+You can change that by modifying `data/conf/sogo/sogo.conf`:
+
+Search...
+```
+   // SOGoDomainsVisibility = (
+    //  (domain1.tld, domain5.tld),
+    //  (domain3.tld, domain2.tld)
+    // );
+```
+...and replace it by - for example:
+
+```
+    SOGoDomainsVisibility = (
+      (example.org, example.com, example.net)
+    );
+```