diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4580c18..cc8212a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - [SECURITY] Additional Nginx directives to prevent access to log files or backup from web browser
 - [CORE] apt-mirror-updater to select the fastest debian/ubuntu mirror with automatic switching between mirrors if the current mirror is being updated
 - [SITE] add `--force` to force Let's Encrypt certificate issuance even if DNS check fail
+- [STACK] check if another mta is installed before installing sendmail
 
 #### Changed
 
diff --git a/wo/cli/plugins/stack.py b/wo/cli/plugins/stack.py
index 5e16aca..956f9f5 100644
--- a/wo/cli/plugins/stack.py
+++ b/wo/cli/plugins/stack.py
@@ -265,11 +265,16 @@ class WOStackController(CementBaseController):
             # sendmail
             if pargs.sendmail:
                 Log.debug(self, "Setting apt_packages variable for Sendmail")
-                if not WOAptGet.is_installed(self, 'sendmail'):
+                if (not WOAptGet.is_installed(self, 'sendmail') and
+                        not WOAptGet.is_installed(self, 'postfix')):
                     apt_packages = apt_packages + ["sendmail"]
                 else:
-                    Log.debug(self, "Sendmail already installed")
-                    Log.info(self, "Sendmail already installed")
+                    if WOAptGet.is_installed(self, 'sendmail'):
+                        Log.debug(self, "Sendmail already installed")
+                        Log.info(self, "Sendmail already installed")
+                    else:
+                        Log.debug(self, "Another mta is already installed")
+                        Log.info(self, "Another mta is already installed")
 
             # proftpd
             if pargs.proftpd: