Images in email signatures – linked or embedded?

Modern HTML email signatures can include images (as well as other multimedia content). Graphics can be included as:

• Linked (online) images: these images aren’t a part of an email signature itself but are stored somewhere on the Internet. To add them to your signature, you need to provide an address (URL) to their location. When you send an email, such images are sent to the recipient as mere links – to see the images, the recipient needs to download them when they open your email (unless they previously set up automatic downloads for images in communications from you).
• Embedded (inline) images: these images are included within the email body rather than being linked from an external source. After you add (embed) images to your email signature, they become an integral part of an email – this ensures embedded images are always automatically displayed when recipients open emails from you.

See the table below to learn about the advantages and disadvantages of each type of images:

Which type of images should I choose?

With years of customer feedback and expertise, we’ve found that embedded images perform better for most common email signature scenarios. They are an integral part of an email, which makes them more reliable – your recipients don’t need to do anything to see your email signatures exactly the way you designed them (Fig. 1.). That’s why we recommend embedding your company logo, social media icons, marketing banners or other images in your email signatures. These elements are typically small in size (e.g. less than 0.5 MB), so they won’t significantly increase your email size.

Fig. 1. Email signature with embedded images (left) vs. linked/online images (right) – to see online images, your recipient must click the highlighted message first.

On the other hand, linked/online images should be chosen if you are concerned about the size of your emails. For example, if you want to include a high-resolution product image that is large (e.g. above 1 MB), it’s better to use an online image hosted on your server or website to avoid clogging your and your recipients’ mailboxes with large data files, even if you don’t send many emails.

Common problems with linked and embedded images

To further help you decide which image type – linked or embedded – to use in your email signatures, here we're listing some common problems that might occur on your recipients’ end.

Linked images:

• Images are not shown and must be downloaded
• Images are not shown and must be unblocked

Embedded images:

• Images are removed when someone replies in Apple Mail
• Images are restored to original size when replying

Images are not shown and must be downloaded by the recipient

Most email apps, including the ones most widely used in business like Outlook, will not show linked images by default, making the first impression of your email signature far from intended. To display the signature in its full glory, the recipients need to download the images first (Fig. 2.).

Fig. 2. Recipients are prompted to download linked images.

Since linked (external) images are by default treated as unsafe, requiring recipient’s action, the best idea is to use the embedded images instead.

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Images are not shown and must be unblocked manually

More and more email apps by default block images that are hosted externally. This problem is likely to occur when you contact someone new, as modern email security mechanisms might treat linked images as potential phishing attempts. This can create a poor first impression when contacting potential clients (Fig. 3.).

Fig. 3. Images are blocked and your recipient needs to unblock them.

To avoid this and ensure you make the best impression possible, use embedded and not linked images in your email signatures.

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Images are removed when someone replies in Apple Mail

Apple Mail tends to remove embedded images when your recipient replies to your email (see the video below). Note that the images are normally visible to the recipient before they reply.

Video: Images disappear when your recipient replies to your email in Mail on an Apple device.

If possible, encourage recipients to use Outlook for iOS or Mac instead. It integrates more smoothly with Microsoft 365 and is immune to this issue. Outlook is the recommended email app to use with Microsoft 365 (Exchange Online) email and offers the deepest integration with features like message recalling and so on.

See the other ways to solve this problem on your and your recipient’s end

Images are restored to original size when replying

When adding a large image to your signature, you can resize it in your email signature editor to make it fit your signature design. However, some email apps (like Apple Mail) may restore the image to its original size when the recipient replies. As a result, the layout of your signature will get corrupted (Fig. 4.).

Fig. 4. Image restored to its full size when a user replies in Apple Mail on Mac.

Apart from asking your recipient to switch to an email app that’s immune to the problem (e.g. Outlook for iOS or Mac), you can follow this general rule: Add images to your email signature in the size you want them to be shown at all times. To this end, scale your image down in a graphical tool of your choice (e.g. GIMP, Paint, etc.) before adding them to your email signature. Even though it might impact the image quality a bit, it ensures the image will always appear at the correct size.

Learn more about the problem with image scaling and how to scale an image down in a graphical tool

See also:

• How to fix common image-related problems in signatures