diff --git a/linux/README.md b/linux/README.md
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@@ -8,4 +8,6 @@
 
 [Bash Scripting](linux-bash-scripting.md)
 
+[Sendmail](linux-sendmail.md)
+
 [VIM](linux-vim.md)
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diff --git a/linux/linux-sendmail.md b/linux/linux-sendmail.md
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+---
+gitea: none
+include_toc: true
+---
+# Sendmail
+
+```
+apt install sendmail
+```
+
+## config
+
+  - change first line of `/etc/hosts` to:\
+    `127.0.0.1 localhost.localdomain localhost backup`\
+    ("backup" is the hostname. Get it with: $ hostname
+  - config\ `sudo sendmailconfig # answer "Y" to everything`
+
+## custom "from: " address
+
+in order to have a custom "from: " email address (instead of `user@localhost.localdomain`) do the following:
+
+  - create file `/etc/mail/genericstable`
+  - add following content:
+    ```
+    user       notifications@docuteam.ch
+    root       notifications@docuteam.ch
+    ```
+  - create `genericstable.db`\
+    `makemap hash /etc/mail/genericstable < /etc/mail/genericstable`
+  - modify `/etc/mail/sendmail.mc`\
+    add following lines right before `MAILER_DEFINITIONS`:\
+    ```
+    FEATURE(`genericstable')dnl`
+    GENERICS_DOMAIN(`localhost.localdomain')dnl
+    ````
+  - macro erstellen\
+    `m4 sendmail.mc > sendmail.cf`
+  - restart sendmail service\
+    `systemctl restart sendmail.service`
+  - test mail\
+    `echo "Subject: sendmail test 1" | sendmail -v r.rutishauser@docuteam.ch`
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