How to embed image using cid in mail body

Embedding an image using a CID (Content ID) in the body of an email involves several steps:

Step 1: Convert the image to a MIME-encoded attachment

You need to convert the image file to a MIME-encoded attachment. You can use a library or tool to do this. For example, in Python, you can use the mimetypes and email.mime modules:

import mimetypes
from email.mime.multipart import MIMEMultipart
from email.mime.image import MIMEImage

image_file = open('image.jpg', 'rb')
mimetype, _ = mimetypes.guess_type(image_file.name)
if mimetype is None:
    mimetype = 'image/jpeg'

msg = MIMEMultipart()
msg['Content-Type'] = f'multipart/related; boundary="{mimetype}"'
msg['Content-Disposition'] = 'inline; filename="image.jpg"'

image = MIMEImage(image_file.read(), mimetype=mimetype)
msg.attach(image)

Step 2: Generate a CID

Generate a unique CID for the image. You can use a random number generator or a UUID library:

import uuid

cid = f'<{uuid.uuid4().hex}>'

Step 3: Add the CID to the image attachment

Add the CID to the image attachment:

image.add_header('Content-ID', cid)

Step 4: Add the image attachment to the email body

Add the image attachment to the email body:

msg.attach(image)

Step 5: Set the Content-Type header

Set the Content-Type header of the email to multipart/related:

msg['Content-Type'] = 'multipart/related; boundary="----BOUNDARY----"'

Step 6: Set the boundary parameter

Set the boundary parameter to a unique string:

boundary = '----BOUNDARY----'
msg['Content-Type'] = f'multipart/related; boundary="{boundary}"'

Step 7: Send the email

Send the email using your preferred email library or service.

Here's the complete code example:

import mimetypes
from email.mime.multipart import MIMEMultipart
from email.mime.image import MIMEImage
import uuid

image_file = open('image.jpg', 'rb')
mimetype, _ = mimetypes.guess_type(image_file.name)
if mimetype is None:
    mimetype = 'image/jpeg'

msg = MIMEMultipart()
msg['Content-Type'] = f'multipart/related; boundary="{mimetype}"'
msg['Content-Disposition'] = 'inline; filename="image.jpg"'

cid = f'<{uuid.uuid4().hex}>'
image = MIMEImage(image_file.read(), mimetype=mimetype)
image.add_header('Content-ID', cid)
msg.attach(image)

msg['Content-Type'] = 'multipart/related; boundary="----BOUNDARY----"'
boundary = '----BOUNDARY----'
msg['Content-Type'] = f'multipart/related; boundary="{boundary}"'

# Send the email using your preferred email library or service

When the email is received, the image will be embedded in the body using the CID. The recipient's email client will display the image inline.

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How to embed image using cid in mail body