Class

What is This Library?

This library provides functionality to send internet mail via SMTP, the Simple Mail Transfer Protocol. For details of SMTP itself, see [RFC2821] (www.ietf.org/rfc/rfc2821.txt).

What is This Library NOT?

This library does NOT provide functions to compose internet mails. You must create them by yourself. If you want better mail support, try RubyMail or TMail or search for alternatives in RubyGems.org or The Ruby Toolbox.

FYI: the official documentation on internet mail is: [RFC2822] (www.ietf.org/rfc/rfc2822.txt).

Examples

Sending Messages

You must open a connection to an SMTP server before sending messages. The first argument is the address of your SMTP server, and the second argument is the port number. Using SMTP.start with a block is the simplest way to do this. This way, the SMTP connection is closed automatically after the block is executed.

require 'net/smtp'
Net::SMTP.start('your.smtp.server', 25) do |smtp|
  # Use the SMTP object smtp only in this block.
end

Replace ‘your.smtp.server’ with your SMTP server. Normally your system manager or internet provider supplies a server for you.

Then you can send messages.

msgstr = <<END_OF_MESSAGE
From: Your Name <your@mail.address>
To: Destination Address <someone@example.com>
Subject: test message
Date: Sat, 23 Jun 2001 16:26:43 +0900
Message-Id: <unique.message.id.string@example.com>

This is a test message.
END_OF_MESSAGE

require 'net/smtp'
Net::SMTP.start('your.smtp.server', 25) do |smtp|
  smtp.send_message msgstr,
                    'your@mail.address',
                    'his_address@example.com'
end

Closing the Session

You MUST close the SMTP session after sending messages, by calling the finish method:

# using SMTP#finish
smtp = Net::SMTP.start('your.smtp.server', 25)
smtp.send_message msgstr, 'from@address', 'to@address'
smtp.finish

You can also use the block form of SMTP.start/SMTP#start. This closes the SMTP session automatically:

# using block form of SMTP.start
Net::SMTP.start('your.smtp.server', 25) do |smtp|
  smtp.send_message msgstr, 'from@address', 'to@address'
end

I strongly recommend this scheme. This form is simpler and more robust.

HELO domain

In almost all situations, you must provide a third argument to SMTP.start/SMTP#start. This is the domain name which you are on (the host to send mail from). It is called the “HELO domain”. The SMTP server will judge whether it should send or reject the SMTP session by inspecting the HELO domain.

Net::SMTP.start('your.smtp.server', 25
                helo: 'mail.from.domain') { |smtp| ... }

SMTP Authentication

The Net::SMTP class supports three authentication schemes; PLAIN, LOGIN and CRAM MD5. (SMTP Authentication: [RFC2554]) To use SMTP authentication, pass extra arguments to SMTP.start/SMTP#start.

# PLAIN
Net::SMTP.start('your.smtp.server', 25
                user: 'Your Account', secret: 'Your Password', authtype: :plain)
# LOGIN
Net::SMTP.start('your.smtp.server', 25
                user: 'Your Account', secret: 'Your Password', authtype: :login)

# CRAM MD5
Net::SMTP.start('your.smtp.server', 25
                user: 'Your Account', secret: 'Your Password', authtype: :cram_md5)
Constants
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Authentication

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Attributes
Read & Write

Set whether to use ESMTP or not. This should be done before calling start. Note that if start is called in ESMTP mode, and the connection fails due to a ProtocolError, the SMTP object will automatically switch to plain SMTP mode and retry (but not vice versa).

Read & Write

Set whether to use ESMTP or not. This should be done before calling start. Note that if start is called in ESMTP mode, and the connection fails due to a ProtocolError, the SMTP object will automatically switch to plain SMTP mode and retry (but not vice versa).

Read

The address of the SMTP server to connect to.

Read

The port number of the SMTP server to connect to.

Read & Write

Seconds to wait while attempting to open a connection. If the connection cannot be opened within this time, a Net::OpenTimeout is raised. The default value is 30 seconds.

Seconds to wait while reading one block (by one read(2) call). If the read(2) call does not complete within this time, a Net::ReadTimeout is raised. The default value is 60 seconds.

Class Methods

The default SMTP port number, 25.

No documentation available

The default mail submission port number, 587.

The default SMTPS port number, 465.

Creates a new Net::SMTP object.

address is the hostname or ip address of your SMTP server. port is the port to connect to; it defaults to port 25.

This method does not open the TCP connection. You can use SMTP.start instead of SMTP.new if you want to do everything at once. Otherwise, follow SMTP.new with SMTP#start.

Creates a new Net::SMTP object and connects to the server.

This method is equivalent to:

Net::SMTP.new(address, port).start(helo: helo_domain, user: account, secret: password, authtype: authtype, tls_verify: flag, tls_hostname: hostname)

Example

Net::SMTP.start('your.smtp.server') do |smtp|
  smtp.send_message msgstr, 'from@example.com', ['dest@example.com']
end

Block Usage

If called with a block, the newly-opened Net::SMTP object is yielded to the block, and automatically closed when the block finishes. If called without a block, the newly-opened Net::SMTP object is returned to the caller, and it is the caller’s responsibility to close it when finished.

Parameters

address is the hostname or ip address of your smtp server.

port is the port to connect to; it defaults to port 25.

helo is the HELO domain provided by the client to the server (see overview comments); it defaults to ‘localhost’.

The remaining arguments are used for SMTP authentication, if required or desired. user is the account name; secret is your password or other authentication token; and authtype is the authentication type, one of :plain, :login, or :cram_md5. See the discussion of SMTP Authentication in the overview notes. If tls_verify is true, verify the server’s certificate. The default is true. If the hostname in the server certificate is different from address, it can be specified with tls_hostname.

Errors

This method may raise:

Instance Methods
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Returns supported authentication methods on this server. You cannot get valid value before opening SMTP session.

true if server advertises AUTH CRAM-MD5. You cannot get valid value before opening SMTP session.

true if server advertises AUTH LOGIN. You cannot get valid value before opening SMTP session.

true if server advertises AUTH PLAIN. You cannot get valid value before opening SMTP session.

true if server advertises STARTTLS. You cannot get valid value before opening SMTP session.

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CRAM-MD5: [RFC2195]

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This method sends a message. If msgstr is given, sends it as a message. If block is given, yield a message writer stream. You must write message before the block is closed.

# Example 1 (by string)
smtp.data(<<EndMessage)
From: john@example.com
To: betty@example.com
Subject: I found a bug

Check vm.c:58879.
EndMessage

# Example 2 (by block)
smtp.data {|f|
  f.puts "From: john@example.com"
  f.puts "To: betty@example.com"
  f.puts "Subject: I found a bug"
  f.puts ""
  f.puts "Check vm.c:58879."
}

WARNING: This method causes serious security holes. Use this method for only debugging.

Set an output stream for debug logging. You must call this before start.

# example
smtp = Net::SMTP.new(addr, port)
smtp.set_debug_output $stderr
smtp.start do |smtp|
  ....
end
An alias for disable_tls

Disables SMTP/TLS (STARTTLS) for this object. Must be called before the connection is established to have any effect.

Disables SMTP/TLS for this object. Must be called before the connection is established to have any effect.

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Enables SMTP/TLS (STARTTLS) for this object. context is a OpenSSL::SSL::SSLContext object.

Enables SMTP/TLS (STARTTLS) for this object if server accepts. context is a OpenSSL::SSL::SSLContext object.

Enables SMTP/TLS (SMTPS: SMTP over direct TLS connection) for this object. Must be called before the connection is established to have any effect. context is a OpenSSL::SSL::SSLContext object.

Finishes the SMTP session and closes TCP connection. Raises IOError if not started.

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Provide human-readable stringification of class state.

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Opens a message writer stream and gives it to the block. The stream is valid only in the block, and has these methods:

puts(str = ”)

outputs STR and CR LF.

print(str)

outputs STR.

printf(fmt, *args)

outputs sprintf(fmt,*args).

write(str)

outputs STR and returns the length of written bytes.

<<(str)

outputs STR and returns self.

If a single CR (“r”) or LF (“n”) is found in the message, it is converted to the CR LF pair. You cannot send a binary message with this method.

Parameters

from_addr is a String representing the source mail address.

to_addr is a String or Strings or Array of Strings, representing the destination mail address or addresses.

Example

Net::SMTP.start('smtp.example.com', 25) do |smtp|
  smtp.open_message_stream('from@example.com', ['dest@example.com']) do |f|
    f.puts 'From: from@example.com'
    f.puts 'To: dest@example.com'
    f.puts 'Subject: test message'
    f.puts
    f.puts 'This is a test message.'
  end
end

Errors

This method may raise:

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Set the number of seconds to wait until timing-out a read(2) call.

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Aborts the current mail transaction

Sends msgstr as a message. Single CR (“r”) and LF (“n”) found in the msgstr, are converted into the CR LF pair. You cannot send a binary message with this method. msgstr should include both the message headers and body.

from_addr is a String representing the source mail address.

to_addr is a String or Strings or Array of Strings, representing the destination mail address or addresses.

Example

Net::SMTP.start('smtp.example.com') do |smtp|
  smtp.send_message msgstr,
                    'from@example.com',
                    ['dest@example.com', 'dest2@example.com']
end

Errors

This method may raise:

An alias for tls?
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Opens a TCP connection and starts the SMTP session.

Parameters

helo is the HELO domain that you’ll dispatch mails from; see the discussion in the overview notes.

If both of user and secret are given, SMTP authentication will be attempted using the AUTH command. authtype specifies the type of authentication to attempt; it must be one of :login, :plain, and :cram_md5. See the notes on SMTP Authentication in the overview. If tls_verify is true, verify the server’s certificate. The default is true. If the hostname in the server certificate is different from address, it can be specified with tls_hostname.

Block Usage

When this methods is called with a block, the newly-started SMTP object is yielded to the block, and automatically closed after the block call finishes. Otherwise, it is the caller’s responsibility to close the session when finished.

Example

This is very similar to the class method SMTP.start.

require 'net/smtp'
smtp = Net::SMTP.new('smtp.mail.server', 25)
smtp.start(helo: helo_domain, user: account, secret: password, authtype: authtype) do |smtp|
  smtp.send_message msgstr, 'from@example.com', ['dest@example.com']
end

The primary use of this method (as opposed to SMTP.start) is probably to set debugging (set_debug_output) or ESMTP (esmtp=), which must be done before the session is started.

Errors

If session has already been started, an IOError will be raised.

This method may raise:

true if the SMTP session has been started.

No documentation available

Returns truth value if this object uses STARTTLS. If this object always uses STARTTLS, returns :always. If this object uses STARTTLS when the server support TLS, returns :auto.

true if this object uses STARTTLS.

true if this object uses STARTTLS when server advertises STARTTLS.

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true if this object uses SMTP/TLS (SMTPS).

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