Embedded vs hosted images in email signatures

Many people are lost when it comes to some tasks like including images in email signatures. Even when you’ve mastered that, something more complex like the discussion between embedded vs hosted images in email signatures can throw you again. 

There’s often a lack of understanding about embedded and hosted images. But it’s not as complex as you may have thought. To put it simply, embedded images are those that are stored within an email. Hosted images are downloaded and stored on a web server. This reduces the size of the email, making it more mobile-friendly. 

Hosting images in email signatures - What’s best?  

To include HTML images in email signatures like a company logo or social media icons, you’ve got two image options. You can either embed an image directly into the email signature template or host it externally and link to it. 

Most email clients can display images in email signatures without any significant issues. However, when creating a signature template, there are benefits to choosing one method over the other. That’s the argument that people have when it comes to embedded vs hosted images in email signatures, and we’re here to help you find what suits you best. 

Embedded images 

• Microsoft 365 (Office 365) - No

• Google Workspace (G Suite) - Yes

• Exchange 2019 - No

• Exchange 2016 - No

• Exchange 2013 or earlier - No

• Outlook 2019 - Yes

• Outlook 2016 - Yes

• Outlook 2013 or earlier - Yes

• OWA (Outlook Web App) - No

• Gmail - Yes

• Outlook.com - No

Hosted images

• Microsoft 365 (Office 365) - Yes

• Google Workspace (G Suite) - Yes

• Exchange 2019 - Yes

• Exchange 2016 - Yes

• Exchange 2013 or earlier - Yes

• Outlook 2019 - Yes

• Outlook 2016 - Yes

• Outlook 2013 or earlier - Yes

• OWA (Outlook Web App)* - No

• Gmail - Yes

• Outlook.com** - No

* To add a linked image, you need to open the image in a browser and copy it into the Office 365 (now Microsoft 365) OWA signature editor. 

** You can add a hosted image by adding the HTML source via the signature editor. 

How to embed images in email signatures 

If you want an image to appear without the recipient having to click a ‘Download Images’ button, we recommend embedding it within the email signature.

This is when an image file is attached to an email and referenced using a Content-ID (HTML image tags). 

A standard Content-ID will look like this: 

<img src="cid:myimagecid" /> 

When an email client refers to these images in email signatures, they’ll be displayed automatically. This is because they’re referenced in the source of the message. 

However, when you add images to email signatures for Outlook, Gmail, and other email clients, the size of the messages increases.

This means there’s a risk that the images will appear as separate attachments in some email clients. There are also known issues with images being stripped out of emails and increasing in size on iOS devices. 

How to host images in email signatures 

If you don’t want email signature images to appear as attachments, we recommend saving and hosting them. You can do this on a web server or via a free image hosting site like Imgur or Flickr. They’ll then be referenced in the email using a web URL. This is known as hosting or linking images: 

A hosted/linked image would typically look like this: 

<img src="https://cdn.exclaimer.com/Static2/exclaimer-logo_178x36.png" /> 

By doing this, your images are never a physical part of the email. Instead, they’re essentially downloaded into the message every time it’s viewed, making the email file size smaller. 

It’s also recommended that you add alt text (alternative text) to any image you host. This way, the recipient will still be able to make sense of the image if they can’t view it. Adding alt text looks like this: 

<img src="https://cdn.exclaimer.com/Static2/exclaimer-logo_178x36.png" alt="Exclaimer logo"/>

However, when using image hosting for your email signatures, a recipient may need to manually click a ‘Download Images’ button for the images to display. This is a way of protecting the recipient against possible viruses. 

Which option should I choose to show images in email signatures? 

You need to consider how your customers/clients view the emails you send them. If many use email clients like Outlook365, embedding images in email signatures is recommended. However, you should use hosted imagery if you know that many recipients will be viewing your emails on mobile devices. 

Of course, if you don’t want to ever have to worry about which option you should choose, use an email signature generator/solution.