gosend

gosend is a command line SMTP client written in Go to send e-mails over STARTTLS or SSL/TLS. It supports plain text, HTML and attachments. It is available for Linux, MacOS, Windows, FreeBSD, OpenBSD, NetBSD for the architectures i386, amd64 and arm64.

Flag Options

• -help: Show flag options.
• -version: Show version.

Server

• -server-file value: Path to settings file.
• -smtp-host value: Hostname of SMTP server.
• -smtp-port value: TCP port of SMTP server.
• -rootca value: File path to X.509 certificate in PEM format for the Root CA when using a self-signed certificate on the mail server.
• -security value: Security protocol (STARTTLS, SSL/TLS).

Authentication

• -auth-file value: Path to authentication file.
• -auth-method value: Authentication Method (plain, CRUM-MD5).
• -login string: Login username.
• -password string: Login password.

Message Header

• -sender value: Email address of sender.
• -to value: Recipient TO address. Comma separate multiple email addresses or use multiple -to options.
• -cc value: Recipient CC address. Comma separate multiple email addresses or use multiple -cc options.
• -bcc value: Recipient BCC address. Comma separate multiple email addresses or use multiple -bcc options.
• -reply-to: Reply-To address. Comma separate multiple email addresses or use multiple -reply-to options.
• -message-id: Custom Message-ID.
• -header: Custom header. Multiple -header flags are allowed..
• -subject string: Email subject.

Message Body

• -body-html string: Body content in HTML.
• -body-text string: Body content in plain text. Add new lines as \n.
• -attachment value: File path to attachment. Comma separate multiple attachments or use multiple -attachment options.

Notes

• Authentication method plain requires a secure connection (except for localhost).
• New lines in the body-text and body-html are supported by inserting \n in your text. These wil be converted to CR LF in your e-mail message.
• Double quotes need to be escaped by using a backslash. e.g. \".
• To send your e-mail to multiple recipients you can either use multiple -tooptions or a -tooption with comma separated addresses.
• To send multiple attachments you can either use multiple -attachmentoptions or a -attachmentoption with comma separated files.
• Attachments can be embedded in HTML by referring to the attachment using its file name. This may include the path to the file as defined in -attachment. The file name with optional path is expected to be enclosed between double quotes.
• -rootcacan be used when your mail server is using a self-signed certificate.
  • The X.509 certificate must be a PEM container file.
  • Use Subject Alternative Name (SAN) fields in your self-signed certificate.
• Normally the SMTP server creates a Message-ID for you. You can use -message-id when replying to an existing message to preserve the thread.

Example

./gosend \
 -smtp-host mail.example.com  \
 -smtp-port 587  \
 -security STARTTLS \
 -auth-method plain \
 -login "your_username" \
 -password "your_password" \
 -sender "Sender<[email protected]>" \
 -to [email protected] -to "[email protected], [email protected]" \
 -cc "[email protected]" \
 -header "X-Test: Test" \
 -subject "Your subject" \
 -body-text "Hi\n\nThis a plain text message." \
 -body-html "<h1>Hi</h1><p>This is a HTML message</p><img src=\"myimage.jpg\" alt=\"My image\">" \
 -attachment "images/myimage.jpg"

Settings Files

With the flags -server-file and -auth-file you can point to a settings file which contains the desired settings for the server and authentication.

Supported flags are:

• smtp-host
• smtp-port
• rootca
• security
• auth-method
• login
• password
• sender

Notes

• Use a =to separate the flag and its value. Spaces around the =are optional.
• Values may optionally surrounded by double quotes " "
• Flags given at the command line overrule the flags in the settings file.
• All suported flags may be used in both -server-file and -auth-file.

Example

security="ssl-tls"
auth-method="plain"
smtp-host="mail.example.com"
smtp-port=587