i think i solved the problem..here are the steps:
1. create a new signature
2. send out a test email and you should see the problem
3. go to preference, then fonts and colours, under message font, choose a font size that you're not going to use, say 36
4. go back to the signature that you just created, you should see that the font of the signature was automatically changed to 36 too..now select the signature texts, right click and choose font->show fonts, then change the font size to your desired size, say 13
5. send out a test email and the font size of the email content should be 36 while the font size of signature should be 13
6. go to the preference again and change the message font to your desired font size, say 13 as to be the same as signature
7. send out a test email again and now you should see that everything is working perfectly!![]()
This worked for me. Thanks