Python SMTP Sending Email

SMTP (Simple Mail Transfer Protocol) is a simple mail transfer protocol. It is a set of rules for transferring mail from a source address to a destination address, which controls the way mail is relayed.

Python's smtplib provides a convenient way to send emails. It is a simple wrapper around the SMTP protocol.

The syntax for creating an SMTP object in Python is as follows:

import smtplib

smtpObj = smtplib.SMTP( [host [, port [, local_hostname]]] )

Parameter description:

• host: SMTP server host. You can specify the IP address or domain name of the host, such as: example.com. This is an optional parameter.
• port: If you provide the host parameter, you need to specify the port number used by the SMTP service. Generally, the SMTP port number is 25.
• local_hostname: If SMTP is on your local machine, you only need to specify the server address as localhost.

The Python SMTP object uses the sendmail method to send emails. The syntax is as follows:

SMTP.sendmail(from_addr, to_addrs, msg[, mail_options, rcpt_options])

Parameter description:

• from_addr: Sender's email address.
• to_addrs: A list of strings, the email addresses to send to.
• msg: The message to send.

Note the third parameter here: msg is a string representing the email. We know that an email generally consists of a subject, sender, recipient, email content, attachments, etc. When sending an email, pay attention to the format of msg. This format is the format defined in the SMTP protocol.

Example

The following example requires that you have an SMTP-supporting service installed on your machine, such as sendmail.

The following is a simple example of sending an email using Python:

We use three quotes to set the email information. A standard email requires three header fields:From, To, andSubject, each piece of information is separated by a blank line.

We instantiate the SMTP object of the smtplib modulesmtpObjto connect to the SMTP server, and usesendmailmethod to send the message.

Run the above program. If you have installedsendmail (mail transfer agent), it will output:

$ python test.py 
邮件发送成功

Check your inbox (usually in the spam folder) to see the email:

If we do not have sendmail access on our machine, we can also use SMTP access from other email service providers (QQ, NetEase, Google, etc.).

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Sending HTML-format emails with Python

The difference between sending HTML-formatted emails and plain-text emails in Python is that the `_subtype` in MIMEText is set to 'html'. The specific code is as follows:

Run the above program. If you have sendmail installed, it will output:

$ python test.py 
邮件发送成功

Check your inbox (usually in the spam folder) to see the email:

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Python Sending Emails with Attachments

To send an email with attachments, first create a MIMEMultipart() instance, then construct the attachment. If there are multiple attachments, you can construct them in sequence, and finally send it using smtplib.smtp.

$ python test.py 
邮件发送成功

Check your inbox (usually in the spam folder) to see the email:

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Adding Images in HTML Text

In HTML email bodies, adding external links is generally ineffective with email service providers. An example of correctly adding images is as follows:

$ python test.py 
邮件发送成功

Check your inbox (if it is in the spam folder, you may need to move it to the inbox for proper display), and you can see the email:

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Sending Using a Third-party SMTP Service

Here we use the SMTP service of QQ Mail (you can also use 163, Gmail, etc.). The following configuration is required:

QQ Mail sets the password by generating an authorization code:

QQ Mail SMTP server address: smtp.qq.com, SSL port: 465.

In the following example, you need to modify: sender email (your QQ email), password, recipient email (you can send to yourself).

$ python test.py 
邮件发送成功

After successful sending, log in to the recipient's mailbox to view:

For more information, please refer to:https://docs.python.org/2/library/email-examples.html。

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