Why do email signature images show as attachments? Because there are only two ways to put an image in an email, and each has a side effect in some mail apps. An image carried inside the message can be listed as an attachment; an image linked from the web can be blocked until the reader allows it. Knowing which one your signature uses tells you which problem you have, and which fix to choose.
| Embedded | Linked (hosted) | |
|---|---|---|
| Where the image is | Inside the message, as a separate part | On a web server; the message holds its address |
| Shows straight away | Yes | Only once the reader allows pictures |
| Can look like an attachment | In some apps | No |
| Adds to message size | Yes | No |
Neither is wrong. They suit different images, and a signature can use both.
Some mail apps show a paperclip on any message containing embedded images, or list each embedded image under the attachments as well as showing it in place. That is how those apps treat embedded images from any sender, and the sender cannot change it. The fix is to have fewer embedded images, or to link the large ones.
It is well known that Apple Mail on iPhone, iPad and Mac can turn the images in a quoted message into attachments when someone replies. Your email arrived perfectly; their reply shows your logo as a separate file. This happens in the recipient's app after delivery, so nothing on the sending side prevents it, except using linked images, which leave nothing in the message to turn into a file.
Many mail apps, Outlook included, do not download pictures from the internet until the reader allows it, particularly from a new sender. A linked logo shows as an empty box or a download prompt until then. Embedding the logo fixes it, because an embedded image needs no download.
Recipients see the symptom on your email, so it reads as a fault in your signature, and the complaint lands with whoever runs the signature tool. The honest answer is that no single method avoids all three symptoms. The useful thing is to be able to choose for each image, and to know which side effect you are accepting.
Every image in the Footer365 editor has two options, Embed and Host, so you choose for each image:
Footer365 embeds up to 20 images, and up to 5 MB of images in all, in any one message. Anything beyond that, and any image that cannot be fetched at the moment of sending, goes as a link instead. SVG images are always linked, because many mail apps do not show an embedded SVG. Our troubleshooting article on images that arrive as attachments goes through each case.
| Image | Choose | Why |
|---|---|---|
| Logo | Embed | It must show at once, even to a new contact |
| Small social icons | Embed | Small, so they add little to the message |
| Large banner or photo | Host | Full quality without weighing down the message, and never an attachment |
Two more habits help whichever you choose: use fewer images, and give each one alt text, so a reader who sees no picture still knows what was there. Our guide to logos, images and photos covers sizes and alt text.
Send a signed email to an iPhone, an Outlook account and a Gmail account, and reply to it from the iPhone. Compare what arrives with the table above, change the one or two images that misbehave, and the complaint goes away. The free trial lets you run the same test with your own logo before you commit.
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