# File lib/em/protocols/smtpserver.rb, line 348
348:       def process_mail_from sender
349:         if (@@parms[:starttls]==:required and !@state.include?(:starttls))
350:           send_data "550 This server requires STARTTLS before MAIL FROM\r\n"
351:         elsif (@@parms[:auth]==:required and !@state.include?(:auth))
352:           send_data "550 This server requires authentication before MAIL FROM\r\n"
353:         elsif @state.include?(:mail_from)
354:           send_data "503 MAIL already given\r\n"
355:         else
356:           unless receive_sender sender
357:             send_data "550 sender is unacceptable\r\n"
358:           else
359:             send_data "250 Ok\r\n"
360:             @state << :mail_from
361:           end
362:         end
363:       end