Creating a mail. 
                        If succesful, it returns the mail object with an mail_id that is greater than 0 | 
                    POST | 
                    mail | 
                    Int | 
                    Mail to create | 
                    Mail (NULL) | 
                    
                        https://webapi.tmw.at/mail request body: {"MailId":0,"Subject":"Test-Mail","Body":"Test-Mail send by WebApi Version 2.5.5","From":"noreply@tmw.at","To":"exception@tmw.at","CC":null,"Bcc":null,"ForeignKey":null,"ForeignCode":null,"Priority":null,"Status":null,"MailType":null,"ArchiveAttachment":false,"IsBodyHtml":false,"Attachments":null}
                     | 
                
                
                    | Add an attachment to the mail | 
                    POST | 
                    mail_id | 
                    Int | 
                    PrimaryKey of Mail | 
                    Int 
                        PrimaryKey of Attachment | 
                    
                        https://webapi.tmw.at/mail-attachment?mail_id=0&attachment_name=Logo.png
                     | 
                
                
                    | attachment_name | 
                    String | 
                    Filename of the attachment | 
                
                
                    | Attache the file to the request as a stream | 
                    
                         | 
                
                
                    Send a prepared mail. 
                        If succesful, it returns the mail_id | 
                    PUT | 
                    mail_id | 
                    Int | 
                    Mail to send | 
                    Int (NULL) | 
                    
                        https://webapi.tmw.at/mail?mail_id=0
                     |