Create Signature in Hosted Mail Webmail

Login to your webmail and click the icon on the top left ( Figure 1 ): 

 

 Figure 1 

 

 

 Next, click on Mail - -> IMAP Accounts --> and click the icon ( Figure 2 ): 

 

 Figure 2 

 

 Enter your custom signature in the Signature section and then click the OK button at the bottom of the page ( Figure 3 ): 

 Figure 3