diff --git a/docs/ci.md b/docs/ci.md
index f80601a5..2584d4f2 100644
--- a/docs/ci.md
+++ b/docs/ci.md
@@ -19,7 +19,8 @@ The project includes a `.gitlab-ci.yml` that allows you to execute the deploymen
 When starting the pipeline through the GitLab UI, you will be queried for some variables plus the following ones:
 
 - `DOMAIN` = The domain to deploy to.
-- `MAIL_DOMAIN` = The mail domain to use.
+- `MAIL_DOMAIN` = (optional) Specify domain (f.e. root FQDN) for Mail, defaults to `DOMAIN`.
+- `SYNAPSE_DOMAIN` = (optional) Specify domain (f.e. root FQDN) for Synapse, defaults to `DOMAIN`.
 - `NAMESPACE`: Defines into which namespace of your K8s cluster openDesk will be installed
 - `MASTER_PASSWORD_WEB_VAR`: Overwrites value of `MASTER_PASSWORD`
 
diff --git a/docs/getting-started.md b/docs/getting-started.md
index b2a0d91a..efa7e1ca 100644
--- a/docs/getting-started.md
+++ b/docs/getting-started.md
@@ -77,18 +77,27 @@ or via environment variable
 export DOMAIN=my.open.desk
 ```
 
-If the mail domain differs from the domain, the mail
-domain has to be set either via `dev` environment
+Additionally, you can announce/specify an alternative Domain for mail and chat.
+
+As example, your domain is `acme.tld` and you want to send mails with this domain, then you can deploy openDesk to
+`*.opendesk.acme.tld` and send mail as `default.user@acme.tld`.
+Webmail will be accessed via `mail.opendesk.acme.tld` in this scenario.
+The required routing have to be implemented by yourself. 
+Users
+
+The alternative domains have to be set either via `dev` environment
 
 ```yaml
 global:
-  mail_domain: "open.desk"
+  mailDomain: "open.desk"
+  synapseDomain: "open.desk"
 ```
 
 or via environment variable
 
 ```shell
 export MAIL_DOMAIN=open.desk
+export SYNAPSE_DOMAIN=open.desk
 ```
 
 ### Apps
diff --git a/helmfile/apps/element/values-matrix-neodatefix-widget.yaml.gotmpl b/helmfile/apps/element/values-matrix-neodatefix-widget.yaml.gotmpl
index 79fc0c10..2d8964f4 100644
--- a/helmfile/apps/element/values-matrix-neodatefix-widget.yaml.gotmpl
+++ b/helmfile/apps/element/values-matrix-neodatefix-widget.yaml.gotmpl
@@ -4,6 +4,7 @@
 configuration:
   bot:
     username: "meetings-bot"
+    homeserver: {{ .Values.global.synapseDomain | default .Values.global.domain }}
 
 containerSecurityContext:
   allowPrivilegeEscalation: false
diff --git a/helmfile/apps/element/values-synapse.yaml.gotmpl b/helmfile/apps/element/values-synapse.yaml.gotmpl
index 47dfb325..133e2e4d 100644
--- a/helmfile/apps/element/values-synapse.yaml.gotmpl
+++ b/helmfile/apps/element/values-synapse.yaml.gotmpl
@@ -29,6 +29,7 @@ configuration:
     password: {{ .Values.databases.synapse.password | default .Values.secrets.postgresql.matrixUser | quote }}
 
   homeserver:
+    serverName: {{ .Values.global.synapseDomain | default .Values.global.domain }}
     appServiceConfigs:
       - as_token: {{ .Values.secrets.intercom.synapseAsToken | quote }}
         hs_token: {{ .Values.secrets.intercom.synapseAsToken | quote }}
diff --git a/helmfile/apps/services/values-postfix.yaml.gotmpl b/helmfile/apps/services/values-postfix.yaml.gotmpl
index 64b90492..56eacd4e 100644
--- a/helmfile/apps/services/values-postfix.yaml.gotmpl
+++ b/helmfile/apps/services/values-postfix.yaml.gotmpl
@@ -41,7 +41,7 @@ podSecurityContext:
 postfix:
   amavisHost: ""
   amavisPortIn: ""
-  domain: {{ .Values.global.mailDomain | quote }}
+  domain: {{ .Values.global.mailDomain | default .Values.global.domain }}
   hostname: "postfix"
   inetProtocols: "ipv4"
   milterDefaultAction: "accept"
@@ -67,7 +67,7 @@ postfix:
   {{- else if .Values.clamavSimple.enabled }}
   smtpdMilters: "inet:clamav-simple:7357"
   {{- end }}
-  virtualMailboxDomains: {{ .Values.global.mailDomain | quote }}
+  virtualMailboxDomains: {{ .Values.global.mailDomain | default .Values.global.domain }}
   virtualTransport: "lmtps:dovecot:24"
 
 replicaCount: {{ .Values.replicas.postfix }}
diff --git a/helmfile/apps/univention-management-stack/values-umbrella.yaml.gotmpl b/helmfile/apps/univention-management-stack/values-umbrella.yaml.gotmpl
index 71e57acb..ba8574e4 100644
--- a/helmfile/apps/univention-management-stack/values-umbrella.yaml.gotmpl
+++ b/helmfile/apps/univention-management-stack/values-umbrella.yaml.gotmpl
@@ -6,7 +6,6 @@ global:
   configMapUcr: "ums-stack-data-swp-ucr"
   configMapUcrForced: null
   domain: {{ .Values.global.domain | quote }}
-  mailDomain: {{ .Values.global.mailDomain | quote }}
   imagePullSecrets:
     {{ .Values.global.imagePullSecrets | toYaml | nindent 4 }}
 
@@ -610,7 +609,7 @@ stack-data-ums:
     # The openDesk configuration brings its own UMC policies.
     installUmcPolicies: false
     domainname: {{ .Values.global.domain | quote }}
-    externalMailDomain: {{ .Values.global.mailDomain | quote }}
+    externalMailDomain: {{ .Values.global.mailDomain | default .Values.global.domain }}
     hostname: {{ .Values.global.hosts.univentionManagementStack | quote }}
     ldapHost: {{ .Values.ldap.host | quote }}
     ldapBase: {{ .Values.ldap.baseDn | quote }}
@@ -651,7 +650,7 @@ stack-data-swp:
       {{- end }}
 
     externalDomainName: {{ .Values.global.domain | quote }}
-    externalMailDomain: {{ .Values.global.mailDomain | quote }}
+    externalMailDomain: {{ .Values.global.mailDomain | default .Values.global.domain }}
 
     portalGroupwareLinkBase: {{ printf "https://%s.%s" .Values.global.hosts.openxchange .Values.global.domain | quote }}
     portalFileshareLinkBase: {{ printf "https://%s.%s" .Values.global.hosts.nextcloud .Values.global.domain | quote }}
diff --git a/helmfile/environments/default/global.gotmpl b/helmfile/environments/default/global.gotmpl
index 101a7e36..cb9951f7 100644
--- a/helmfile/environments/default/global.gotmpl
+++ b/helmfile/environments/default/global.gotmpl
@@ -13,7 +13,11 @@ global:
 
   ## Define mail host
   #
-  mailDomain: {{ env "MAIL_DOMAIN" | default "souvap.cloud" | quote }}
+  mailDomain: {{ env "MAIL_DOMAIN" | quote }}
+
+  ## Define synapse host
+  #
+  synapseDomain: {{ env "SYNAPSE_DOMAIN" | quote }}
 
   ## Define docker registry address.
   #