While coding send mail functionality, found that the attachment functionality is not working properly. The attachment is displayed in the Web browser Gmail / Mozilla Thunderbird but when tested with Microsoft Outlook, Apple Mail for a strange it didn't showed any attachment. After a long debug we found that instead of
Content-Type : multipart/related;it should be
Content-Type : multipart/mixed;I am not sure what exactly the difference but it worked out to be a wonder for us. So Please make sure that whenever Attachment is attached thru coding we should use only
Content-Type : multipart/mixed;Hope this might help you whenever you face this kind of problem.