Send emails from Julia



Build Status

A CURL based SMTP client with fairly low level API. It is useful for sending emails from within Julia code. Depends on LibCURL.jl.

The latest version of SMTPClient requires Julia 1.3 or higher. Versions of this package may be available for older Julia versions, but are not fully supported.



The LibCURL native library is automatically installed using Julia's artifact system.


using SMTPClient

opt = SendOptions(
  isSSL = true,
  username = "you@gmail.com",
  passwd = "yourgmailpassword")
#Provide the message body as RFC5322 within an IO
body = IOBuffer(
  "Date: Fri, 18 Oct 2013 21:44:29 +0100\r\n" *
  "From: You \r\n" *
  "To: me@test.com\r\n" *
  "Subject: Julia Test\r\n" *
  "\r\n" *
  "Test Message\r\n")
url = "smtps://smtp.gmail.com:465"
rcpt = ["", ""]
from = ""
resp = send(url, rcpt, from, body, opt)
  • Sending from file IOStream is supported: body = open("/path/to/mail")

Gmail Notes

Due to the security policy of Gmail, you need to "allow less secure apps into your account":

The URL for gmail can be either smtps://smtp.gmail.com:465 or smtp://smtp.gmail.com:587. (Note the extra s in the former.) Both use SSL, and thus isSSL must be set to true in SendOptions. The latter starts the connection with plain text, and converts it to secured before sending any data using a protocol extension called STARTTLS. Gmail documentation suggests using this latter setup.


Since this package is a pretty thin wrapper around a low level network protocol, it helps to know the basics of SMTP while troubleshooting this package. Here is a quick overview of SMTP. In particular, please pay attention to the difference between the envelope headers and the message headers.

If you are having trouble with sending email, set verbose=true when creating the SendOptions object. Please always do this before submitting a bugreport to this project.

When sending email over SSL, certificate verification is performed, which requires the presence of a certificate authority bundle. This package uses the CA bundle from the Mozilla project. Currently there is no way to specify a private CA bundle. Modify the source if you need this.

Function Reference

send(url, to-addresses, from-address, message-body, options)

Send an email.

  • url should be of the form smtp://server:port or smtps://....
  • to-address is a vector of String.
  • from-address is a String. All addresses must be enclosed in angle brackets.
  • message-body must be a RFC5322 formatted message body provided via an IO.
  • options is an object of type SendOptions. It contains authentication information, as well as the option of whether the server requires TLS. SendOptions(; isSSL = false, verbose = false, username = "", passwd = "")

Options are passed via the SendOptions constructor that takes keyword arguments. The defaults are shown above.

  • verbose: enable libcurl verbose mode or not.
  • If the username is blank, the passwd is not sent even if present.

Note that no keepalive is implemented. New connections to the SMTP server are created for each message.

First Commit


Last Touched

8 days ago


84 commits


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