Mail dosen't display body when use the content-type 'multipart/alternative'

Hi All,

I received the email with subject line without body content display when use content-type ‘multipart/alternative’

for multipart content type the below steps i have followed

  • Convert the body to bytesToStream,
  • CreateMimeData
  • addBodyPart
  • getEnvelopeStream

from the last step i got the stream data as(
Message-ID: 1233227036.46.1566898788827.JavaMail.UKPDPMC25$@UKPDPMC25\r\nMIME-Version: 1.0\r\nContent-Type: multipart/mixed; \r\n\tboundary="----=_Part_45_1103770656.1566898788827"\r\n\r\n------=_Part_45_1103770656.1566898788827\r\nMessage-ID: 62821586.44.1566898788826.JavaMail.UKPDPMC25$@UKPDPMC25\r\nMIME-Version: 1.0\r\ncontent-type: text/plain\r\ncontent-transfer-encoding: 7bit\r\nDear Andy,\nThis is Coachcard (TravelPass) Email Multiline Input Test\n: Dear Andy,\nThis is Coachcard (TravelPass) Email Multiline Input Test\n\r\n\r\n\r\n------=_Part_45_1103770656.1566898788827–\r\n)

body as in stream but not display on emails. Could someone help me on this? also attached the flow steps