Linux sendmail - LO Man Hei

# sSMTP to send automated email

#### Introduction

[sSMTP](https://wiki.debian.org/sSMTP) is a program which delivers email from a local computer to a configured mailhost (mailhub). It is not a mail server (like feature-rich mail server sendmail) and does not receive mail, expand aliases or manage a queue. One of its primary uses is for forwarding automated email (like system alerts) off your machine and to an external email address.

#### Installation & Configuration

**1. Install by APT**

`sudo apt install ssmtp mailutils`

**2.1 Configure sSMTP (with free, custom domain email provider, [zoho.com](https://www.zoho.com))**

`nano /etc/ssmtp/ssmtp.conf`

```bash
#
# Config file for sSMTP sendmail
#
# The person who gets all mail for userids < 1000
# Make this empty to disable rewriting.
root=username@myDomain.com

# The place where the mail goes. The actual machine name is required no 
# MX records are consulted. Commonly mailhosts are named mail.domain.com
mailhub=smtp.zoho.com:465

# Where will the mail seem to come from?
#rewriteDomain=

# The full hostname
hostname=myDomain.com

# Are users allowed to set their own From: address?
# YES - Allow the user to specify their own From: address
# NO - Use the system generated From: address
FromLineOverride=YES

AuthUser=username@myDomain.com
AuthPass=********

UseTLS=YES

```

AuthPass is **not** the login password. One can be created in the [Security > Application-Specific Passwords](https://accounts.zoho.com/home#security/security_pwd) section.

In case of encountering `sendmail: 553 Relaying disallowed`, configuring **revaliases** may solve the problem:

`nano /etc/ssmtp/revaliases`

```bash
# sSMTP aliases
# 
# Format:       local_account:outgoing_address:mailhub
#
# Example: root:your_login@your.domain:mailhub.your.domain[:port]
# where [:port] is an optional port number that defaults to 25.
root:username@myDomain.com:smtp.zoho.com:465
ubuntu:username@myDomain.com:smtp.zoho.com:465
```

**2.2 Configure sSMTP (with [gmail](https://mail.google.com/))**

```bash
#
# Config file for sSMTP sendmail
#
# The person who gets all mail for userids < 1000
# Make this empty to disable rewriting.
root=username@gmail.com

# The place where the mail goes. The actual machine name is required no 
# MX records are consulted. Commonly mailhosts are named mail.domain.com
mailhub=smtp.gmail.com:587

# Where will the mail seem to come from?
#rewriteDomain=

# The full hostname
hostname=gmail.com

# Are users allowed to set their own From: address?
# YES - Allow the user to specify their own From: address
# NO - Use the system generated From: address
FromLineOverride=YES

AuthUser=username@gmail.com
AuthPass=********

UseSTARTTLS=YES
UseTLS=YES
```

Again, AuthPass is **not** the login password. You can create one with the following steps:

- Access [Google Account Security page](https://myaccount.google.com/security)

- **Allow** Less secure app access

- Setup 2-Step Verification

- Setup App passwords **(Only available when 2-Step Verification is setup)**

#### Verify the Installation

`echo "Subject: hello" | sendmail test@example.com`

Further example, please visit [16 COMMAND EXAMPLES TO SEND EMAIL FROM THE LINUX COMMAND LINE](https://blog.edmdesigner.com/send-email-from-linux-command-line/).

#### Install Add-on ([mpack](https://linux.die.net/man/1/mpack)) [Optional]

With **mpack**, you may attach a file in MIME format to the mail.

`mpack -s "Hello" file.ext test@example.com`

Further example, please visit [mpack(1) - Linux man page](https://linux.die.net/man/1/mpack)

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