send_mail: Send email

In curl: A Modern and Flexible Web Client for R

Send email

Description

Use the curl SMTP client to send an email. The message argument must be properly formatted RFC2822 email message with From/To/Subject headers and CRLF line breaks.

Usage

send_mail(
  mail_from,
  mail_rcpt,
  message,
  smtp_server = "smtp://localhost",
  use_ssl = c("try", "no", "force"),
  verbose = TRUE,
  ...
)

Arguments

mail_from	email address of the sender.
mail_rcpt	one or more recipient email addresses. Do not include names, these go into the message headers.
message	either a string or connection with (properly formatted) email message, including sender/recipient/subject headers. See example.
smtp_server	hostname or address of the SMTP server, or, an ⁠smtp://⁠ or ⁠smtps://⁠ URL. See "Specifying the server, port, and protocol" below.
use_ssl	Request to upgrade the connection to SSL using the STARTTLS command, see CURLOPT_USE_SSL for details. Default will try to SSL, proceed as normal otherwise.
verbose	print output
...	other options passed to handle_setopt(). In most cases you will need to set a username and password or login_options to authenticate with the SMTP server, see details.

Specifying the server, port, and protocol

The smtp_server argument takes a hostname, or an SMTP URL:

• mail.example.com - hostname only

• mail.example.com:587 - hostname and port

• ⁠smtp://mail.example.com⁠ - protocol and hostname

• ⁠smtp://mail.example.com:587⁠ - full SMTP URL

• ⁠smtps://mail.example.com:465⁠ - full SMTPS URL

By default, the port will be 25, unless ⁠smtps://⁠ is specified–then the default will be 465 instead.

For internet SMTP servers you probably need to pass a username and passwords option. For some servers you also need to pass a string with login_options for example login_options="AUTH=NTLM".

Encrypting connections via SMTPS or STARTTLS

There are two different ways in which SMTP can be encrypted: SMTPS servers run on a port which only accepts encrypted connections, similar to HTTPS. Alternatively, a regular insecure smtp connection can be "upgraded" to a secure TLS connection using the STARTTLS command. It is important to know which method your server expects.

If your smtp server listens on port 465, then use a ⁠smtps://hostname:465⁠ URL. The SMTPS protocol guarantees that TLS will be used to protect all communications from the start.

If your email server listens on port 25 or 587, use an ⁠smtp://⁠ URL in combination with the use_ssl parameter to control if the connection should be upgraded with STARTTLS. The default value "try" will opportunistically try to upgrade to a secure connection if the server supports it, and proceed as normal otherwise.

Examples

## Not run: # Set sender and recipients (email addresses only)
recipients <- readline("Enter your email address to receive test: ")
sender <- '[e-mail]'

# Full email message in RFC2822 format
message <- 'From: "R (curl package)" <[e-mail]>
To: "Roger Recipient" <[e-mail]>
Subject: Hello R user!

Dear R user,

I am sending this email using curl.'

# Send the email
send_mail(sender, recipients, message, smtp_server = 'smtps://smtp.gmail.com',
  username = 'curlpackage', password  = 'qyyjddvphjsrbnlm')
## End(Not run)

curl documentation built on June 8, 2025, 11:35 a.m.