1. You can upload a picture to the server e.g. using FTP or file manager found in control panel. If you upload the picture to the root of your public_html, your picture can be found at https://www.yourdomain.fi/logoname.jpg

2. Log in to Webmail and Roundcube and go to Settings -> Identities -> Signature.

3. Make sure that the ‘HTML-signature’ is checked.
After this, click the HTML-button found in the editors toolbar.

Finally, add the following line to the end:

<img src="http://www.yourdomain.fi/logoname.jpg" alt="" />

In this example, the logo name is logoname.jpg.
If you uploaded the picture with a different name or filetype, you need to change the code accordinly.
Also change the “yourdomain.fi” with your domain name.

Step 1 only has to be done once.
Steps 2 and 3 has to be repeated for each email account you wish to have a logo signature.