How can I send a mail message with multiple lines in the body?


You need to manually add the new lines to the message. Try the following:

StringBuffer sb = new StringBuffer();

sb.append("This is line 1

sb.append("This is the second line



You must use one body part with text but the text can contain multiple lines. So you need to use the.

You can also use
String newline = System.getProperty(“line.separator”);
to get the platform-specific line separator. Keep in mind that if you display the text as HTML, the newline is just white space.