diff --git a/docs/ci.md b/docs/ci.md
index 4fd61405..f80601a5 100644
--- a/docs/ci.md
+++ b/docs/ci.md
@@ -4,7 +4,7 @@ SPDX-License-Identifier: Apache-2.0
 -->
 <h1>CI/CD</h1>
 
-This page will cover openDesk automation via Gitlab CI.
+This page covers openDesk deployment automation via Gitlab CI.
 
 <!-- TOC -->
 * [Deployment](#deployment)
@@ -13,29 +13,30 @@ This page will cover openDesk automation via Gitlab CI.
 
 # Deployment
 
-The project includes a `.gitlab-ci.yml` that allows you to execute the deployment from a Gitlab instance of your choice.
+The project includes a `.gitlab-ci.yml` that allows you to execute the deployment from a GitLab instance of your choice.
 
 
-When starting the pipeline through the Gitlab UI, you will be queried for some variables plus the following ones:
+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.
-- `NAMESPACE`: Defines into which namespace of your K8s cluster the SWP will be installed
+- `MAIL_DOMAIN` = The mail domain to use.
+- `NAMESPACE`: Defines into which namespace of your K8s cluster openDesk will be installed
 - `MASTER_PASSWORD_WEB_VAR`: Overwrites value of `MASTER_PASSWORD`
 
 Based on your input, the following variables will be set:
 - `MASTER_PASSWORD` = `MASTER_PASSWORD_WEB_VAR`. If `MASTER_PASSWORD_WEB_VAR`
   is not set, the default for `MASTER_PASSWORD` will be used, unless you set
-  `MASTER_PASSWORD` as a masked CI/CD variable in Gitlab to supersede the default.
+  `MASTER_PASSWORD` as a masked CI/CD variable in GitLab to supersede the default.
 
-You might want to set credential variables in the Gitlab project at `Settings` > `CI/CD` > `Variables`.
+You might want to set credential variables in the GitLab project at `Settings` > `CI/CD` > `Variables`.
 
 # Tests
 
-The gitlab-ci pipeline contains a job named `run-tests` that can trigger a test suite pipeline on another gitlab project.
+The GitLab CI pipeline contains a job named `run-tests` that can trigger a test suite pipeline on another GitLab project.
 The `DEPLOY_`-variables are used to determine which components should be tested.
-In order for the trigger to work, the variable `TESTS_PROJECT_URL` has to be set on this gitlab project's CI variables
+In order for the trigger to work, the variable `TESTS_PROJECT_URL` has to be set on this GitLab project's CI variables
 that can be found at `Settings` -> `CI/CD` -> `Variables`. The variable should have this format:
 `<domain of gitlab>/api/v4/projects/<id>`.
 
-If the branch of the test pipeline is not `main` this can be set with the .gitlab-ci.yml variable
+If the branch of the test pipeline is not `main` this can be set with the `.gitlab-ci.yml` variable
 `TESTS_BRANCH` while creating a new pipeline.
diff --git a/docs/getting-started.md b/docs/getting-started.md
index fa321a50..b2a0d91a 100644
--- a/docs/getting-started.md
+++ b/docs/getting-started.md
@@ -77,6 +77,20 @@ 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
+
+```yaml
+global:
+  mail_domain: "open.desk"
+```
+
+or via environment variable
+
+```shell
+export MAIL_DOMAIN=open.desk
+```
+
 ### Apps
 
 All available apps and their default value can be found in `helmfile/environments/default/workplace.yaml`.
diff --git a/helmfile/apps/services/values-postfix.yaml.gotmpl b/helmfile/apps/services/values-postfix.yaml.gotmpl
index 2e3ea506..64b90492 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.domain | quote }}
+  domain: {{ .Values.global.mailDomain | quote }}
   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.domain | quote }}
+  virtualMailboxDomains: {{ .Values.global.mailDomain | quote }}
   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 6259c789..71e57acb 100644
--- a/helmfile/apps/univention-management-stack/values-umbrella.yaml.gotmpl
+++ b/helmfile/apps/univention-management-stack/values-umbrella.yaml.gotmpl
@@ -6,6 +6,7 @@ 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 }}
 
@@ -609,7 +610,7 @@ stack-data-ums:
     # The openDesk configuration brings its own UMC policies.
     installUmcPolicies: false
     domainname: {{ .Values.global.domain | quote }}
-    externalMailDomain: {{ .Values.global.domain | quote }}
+    externalMailDomain: {{ .Values.global.mailDomain | quote }}
     hostname: {{ .Values.global.hosts.univentionManagementStack | quote }}
     ldapHost: {{ .Values.ldap.host | quote }}
     ldapBase: {{ .Values.ldap.baseDn | quote }}
@@ -650,7 +651,7 @@ stack-data-swp:
       {{- end }}
 
     externalDomainName: {{ .Values.global.domain | quote }}
-    externalMailDomain: {{ .Values.global.domain | quote }}
+    externalMailDomain: {{ .Values.global.mailDomain | quote }}
 
     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 }}