Line length is an issue in plain text format messages and in rich-text format (RTF) messages sent to recipients whose entries in your address book are not set up for RTF. It is not an issue in HTML messages, except when you send an HTML message to someone whose mail program can't display HTML (like cell phones).
Mail sent to the Internet may use a "content-transfer-encoding" called "quoted-printable," which does not have a fixed line length. Some e-mail programs cannot wrap "quoted-printable" text and, therefore, display it all as one lone line.
On the other hand, if you send mail using a fixed line length, when recipients reply and using Internet-style quoting, the resulting message may have lines that wrap with just one or two words on a line.
Note that the plain text line length settings are totally broken in Outlook 2002, we can offer no instructions for that version.
Set Line Length in Options
To set the line length of plain text messages in Outlook, you need to set the line length in Options.
In Outlook 2013 and Outlook 2010, this setting is in File, Options, Mail. Look for the Message Format section at the bottom of the dialog.
Note: The option to remove extra line breaks applies only to received email, generally making plain text messages wrap nicely in the reading pane.
In Outlook 2007 and Outlook 2003, this setting in under the File, Options, Mail Format tab, Internet Format button.
Outlook 2007, 2010 and 2013
The registry key described in Line Wrapping Does Not Appear As Expected When You Send E-Mail Messages in Outlook 2003 works in Outlook 2007, 2010, and 2013 to control line breaks in email sent using an SMTP server. This does not apply to messages sent using Microsoft Exchange server.
By setting WrapLines to 0, messages will use Quoted-Printable encoding and lines wrap.
For ready-to-run registry files, see Do It For Me below.
The default setting for Outlook 2003 is to insert a hard return at the end of each line in a plain text message. This causes long URLs (ironically including many at microsoft.com) to be unusable in the received message. You can turn off these hard returns (and, by default, use quoted-printable encoding) by adding a WrapLines entry to the Windows registry, as described in this MSKB article:
Line Wrapping Does Not Appear As Expected When You Send E-Mail Messages in Outlook 2003
This article also describes how to control the Internet encoding and the line length if you want hard returns at the ends of lines in plain text messages.
Do It For Me
If you don't want to edit the registry yourself, we have ready-to-run registry files available for Outlook 2003, Outlook 2007, and Outlook 2010. Right click on the version for your computer and chose Save target as or Save link as (FireFox) then run it from your computer. You can click on the link and run it from the webpage but some security software may block it.
Outlook 2000 and 98
In Corporate/Workgroup mode, choose Tools | Options | Internet E-mail and set options as described below.
In Internet Mail Only mode, choose Tools | Options | Mail Format | Settings and set options as described below.
To set a fixed line length:
- Set Encode text using to None.
- Set the line length. The default is 76 characters. Using a shorter line length will probably make your messages look better when people reply to them.
To use quoted-printable (no fixed length):
- Set Encode text using to Quoted Printable.
The original Internet Mail service in Outlook 97 uses only quoted-printable for plain text messages. To be able to set a fixed line length, you must upgrade to version 8.02 or later or download the Internet Mail Enhancement Patch.
To set the fixed line length (IMEP):
- Choose Tools | Options | Internet E-mail.
- Check the box for When sending messages, wrap text at xx characters.
- Set the line length.
I'm not sure that Outlook 97 with IMEP has a quoted-printable option. I think that if you clear the box in Step 2 above, Outlook 97 defaults to a fixed 75-character line.