@Nalins_99 just so I'm clear, this is what you are trying to achieve - 

• As regular case processing on mobile, you captured user's signature via 'Signature Capture' control
• This signature is then stored as attachment of that case
• On case UI, you would be able to view Signature because Signature capture control fetches the attachment and displays signature image on canvas

Now, you want the same functionality in an outgoing email. I'm not sure that is an intended usecase of signature control but I may be wrong. I say this because Signature control does everything in browser to show image on canvas and while sending Correspondence those scripts will not execute. 

@bajaa do you know if this works? Been years since I worked on Signature control.

@Nalins_99

One way to do this would be to fetch that image attachment (signature) from the case and insert it inside Image tag. The src should not be base64 because email clients will reject it or show it as external attachment when email is received by end-users. This image must be saved in Static content directory using Data-Content-Image and that URL must be used as 'src' of image tag. Then email clients will treat this as a proper inline image.