Usage
    subject(sg_mail, subject)
 
    
    Arguments
    - sg_mail
- (required)mail object from package 
- subject
- (required)mail subject 
 
    
    Value
    
sg_mail class with subject.
     
    
    Examples
    mail() %>%
  subject("mrchypark@gmail.com")
#> SendGrid Mail - 
#> ✖   from   : (required)
#> ✖   to     : (required)
#> ✔   subject: nchr[19] mrchypark@gmail.com
#> ✖   content: (required)
#> ✔   attach : (optional)