Webform doesn't send email using MIME Mail My webform forms doesn't send the email if I set Site-wide default MailSystemInterface class to MimeMailSystem. 

It works fine if I set Site-wide default MailSystemInterface class  to DefaultMailSystem

Take a look at my captures: 

I was working fine until yesterday, then all the sudden this problem is happening. 

How can I trace this?
I had a similar, slightly different, issue after updating from webform version 7.x.3.25 to 7.x.3.27 

WORKED FOR ME:

Upgrade to webform 7.x.4-branch