Outlook Reply / Forward prefixes

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Why RE and FW are the best options for email subjects

When you reply or forward a message your email program will add a prefix to the subject line. The question is – do you choose the standard ‘English’ prefixes RE: and FW: or your local equivalents?

There’s plenty of alternatives to RE and FW around the world, just a few we’ve seen are:
































With a well behaved email program, like Outlook, all these replies are considered part of the same email conversation thread even though the subject lines are different:

  • RE: Office-Watch.com
  • AW: Office-Watch.com
  • SV: Office-Watch.com
  • VS: Office-Watch.com
  • ODP: Office-Watch.com
  • R: Office-Watch.com

In our tests, the same subject but different prefixes are all grouped into the one conversation – which is quite right. We have more detail on how Outlook handles subject prefixes below.

However other email clients can’t cope as well with a mix of prefixes from across the globe (or random/unexpected ones). That’s a shame but it’s the way things are and a relic of the mostly American development of Internet email.

It’s best to stick with RE and FW as a courtesy to other people. Outlook lets non-English language users do that with two setting buried in the options.

  • Use English for message flag labels
  • Use English for message headers on replies and forwards [and for forward notifications]

Outlook 2013 and Outlook 2010

Go to File | Options | Advanced | International Options:

Outlook%20Subject%20Prefixes%201 - Outlook Reply / Forward prefixes

Outlook 2007 and before

Tools | Options | Mail Format | International Options

Outlook%20Subject%20Prefixes%202 - Outlook Reply / Forward prefixes

More detail

In Outlook 2013 (probably earlier versions) ANY prefix is ignored in the subject line (when grouping for conversation) as long as it has three letters or less and ends with a colon. Therefore these subject lines will also be grouped with the above examples:

  • X: Office-Watch.com
  • ZZ: Office-Watch.com
  • MFF: Office-Watch.com

But these will not:

  • FRD Office-Watch.com
  • Q7: Office-Watch.com
  • Q!: Office-Watch.com
  • DAGG: Office-Watch.com

Here’s how some test messages appear in Outlook 2013, Inbox sorted by Conversations. Eight messages with varying subject prefixes are grouped together and you can see the four messages that were not recognized as being part of the same conversation.

Outlook%20Subject%20Prefixes%203 - Outlook Reply / Forward prefixes

The four that aren’t grouped because (respectively) of a digit in the prefix, a non-letter in the prefix, no colon after the prefix and prefix too long).

Compare that with an ungrouped view of the same messages on an Android phone

Outlook%20Subject%20Prefixes%204 - Outlook Reply / Forward prefixes

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