How do I format a String in an email so Outlook will print the line breaks?

You need to use \r\n as a solution.

You can force a line break in outlook when attaching one (or two?) tab characters (\t) just before the line break (CRLF).

Example:

This is my heading in the mail\t\n
Just here Outlook is forced to begin a new line.

It seems to work on Outlook 2010. Please test if this works on other versions.

See also Outlook autocleaning my line breaks and screwing up my email format

Microsoft Outlook 2002 and above removes "extra line breaks" from text messages by default (kb308319). That is, Outlook seems to simply ignore line feed and/or carriage return sequences in text messages, running all of the lines together.

This can cause problems if you're trying to write code that will automatically generate an email message to be read by someone using Outlook.

For example, suppose you want to supply separate pieces of information each on separate lines for clarity, like this:

Transaction needs attention!
PostedDate: 1/30/2009
Amount: $12,222.06
TransID: 8gk288g229g2kg89
PostalCode: 91543

Your Outlook recipient will see the information all smashed together, as follows:

Transaction needs attention! PostedDate: 1/30/2009 Amount: $12,222.06 TransID: 8gk288g229g2kg89 ZipCode: 91543

There doesn't seem to be an easy solution. Alternatives are:

1. You can supply two sets of line breaks between each line. That does stop Outlook from combining the lines onto one line, but it then displays an extra blank line between each line (creating the opposite problem). By "supply two sets of line breaks" I mean you should use "\r\n\r\n" or "\r\r" or "\n\n" but not "\r\n" or "\n\r".
2. You can supply two spaces at the beginning of every line in the body of your email message. That avoids introducing an extra blank line between each line. But this works best if each line in your message is fairly short, because the user may be previewing the text in a very narrow Outlook window that wraps the end of each line around to the first position on the next line, where it won't line up with your two-space-indented lines. This strategy has been used for some newsletters.
3. You can give up on using a plain text format, and use an html format.

I had the same issue, and found a solution. Try this: %0D%0A to add a line break.

You need to send HTML emails. With <br />s in the email, you will always have your line breaks.

Try \r\c instead of \n.

EDIT: I think @Robert Wilkinson had it right. \r\n. Memory just isn't what it used to be.

The \n largely works for us, but Outlook does sometimes take it upon itself to remove the line breaks as you say.

I was facing the same issue and here is the code that resolved it:

\t\n - for new line in Email service JavaMailSender

String mailMessage = JSONObject.toJSONString("Your message").replace(",", "\t\n").trim();

RESOLVED IN MY APPLICATION

In my application, I was trying to send an email whose message body was typed by the user in text area. When mail was send, outlook automatically removed line break entered by user.

e.g if user entered
Yadav
Mahesh

outlook displayed it as
YadavMahesh

Resolution: I changed the line break character "\r\n" with "\par " ( remember to hit space at the end of RTF code "\par" )and line breaks are restrored.

Cheers,
Mahesh

Not sure if it was mentioned above but Outlook has a checkbox setting called "Remove extra line breaks in plain text messages" and is checked by default. It is located in a different spot for different versions of Outlook but for 2010 go to the "File" tab. Select "Options => Mail" Scroll down to "Message format" Uncheck the checkbox.