The RoundCube Webmail client supports plain text and HTML signatures that can be automatically added to every outgoing message.
Create and customize your signature in RoundCube as you click on "Settings" and then on the -> "Identities" tab.
Select an existing identity or add a new one so that the settings of the Identities tab will be loaded on the right hand panel.
Here you must fill in information like name (this will be shown in the From: field of the email), email, etc.
If you want to use this identity every time you compose a new message, select the "Set default" option.
Activate the HTML signature option (1) to embed an HTML code in your signature.
Then click on the HTML button (2). The HTML Source Editor will load.
There you can add and edit the HTML code.
You can add image to the signature by inserting an (2) HTML code in the HTML editor such as:
<img src="http://mysitename.com/image.png" alt="mysitename.com" />
You can place the signature image in the hosting account, for example in the public_html directory, and then set the full path to the file.
Sending HTML Emails
In order for the HTML signature to work, you will need to compose and send HTML formatted messages (!).
To enable this feature, access "Settings" -> "Preferences" and select -> "Composing Messages".
For the "Compose HTML messages" select the (!) "always" option from the drop-down menu.
Save your settings by hitting "Save".