Difference Between Embedded and Hosted Images in Email Signatures

Embedded images (aka Inline Images) are appended to the email itself, making them part of the actual email. This is done by inserting the image in the “Content-ID” tag of the HTML code.

When opening emails with embedded images, you don’t have to download the images manually using the “Click here to download images” button (in Outlook), because the images are appended to the email, and not hosted elsewhere. However, the downside of this is the images can also turn into attachments if someone in the email chain converts the email to plain text format.

Here’s an example of the code where an image is embedded:

<img src=”cid:imageid”>

Pros

• Automatically visible when opening an email / no need to manually download images for every email
• The images are visible even if you don’t have an internet connection (but the email is already in your inbox)
• Not affected by external image hosting failures or problems

Cons

• Increases the size of the email since the images are stored in the email itself
• Images can be turned to attachments if the email is converted to plain text format by a recipient
• The email is more likely to be blocked by anti-virus or spam filtering software

Hosted images are publicly available images which are hosted on a web server that anyone can open and view. You can use a hosted image in your email signature by providing a link to it in the <img> tag within the HTML code.

Using hosted images is the preferred and most widely used method when it comes to email signature images. This is because, for large companies, it is more scalable, maintains consistent branding, and allows the email size to be much smaller.

One of the advantages of using hosted images is that no matter what, your images won’t be turned to attachments. If an email is converted to plain text, all that will happen is the link itself will be visible in the email.

Here’s an example of the code where an image is hosted:

<img height=”143″ width=”142″ src=”https://imagehosting.com/img.png”>

Pros

• The size of your email is not increased as the images are stored elsewhere
• Images won’t be turned into attachments even if the email is converted to plain text format
• You can track clicks on your images using Google Analytics

Cons

• Most email clients require the images to be manually downloaded before being visible (eg. “Click here to download pictures” in Outlook)
• The email could be blocked by spam filtering software if the images are hosted on a domain which is blacklisted
• You’re relying on the web server which is hosting the images to be available at all times to serve requests

Should I use embedded or hosted images for my email signature?

The most widely used option for email signatures is hosted images. Using hosted images delivers much better benefits over using embedded images via Content-ID mainly because the size of every email increases dramatically.

If you have the option of using hosted images with your email signature, definitely do that! The only thing to keep in mind is that you should use a reputable web host where you can store your images. If your images are offline or unavailable for any reason, this will make your email signature images not work.

Our free email signature tool stores all of your images on high-availability web servers which means they will always be available to download when an email client requests them.