What Does “RE” Mean in Email?
RE appears in the subject line of an email and indicates that the message is a reply to a previous email in the same conversation.
It is automatically added by most email clients (such as Gmail or Outlook) when you respond to a message.
For example:
Subject: RE: Webinar Registration Confirmation
This tells the recipient that the email is part of an existing thread, not a brand-new message.
What Does “RE” Stand For?
Many people believe “RE” stands for “regarding,” but technically it comes from the Latin word “re”, meaning “in reference to” or “about.”
In modern email usage, however, it simply signals a reply.
Why “RE” Matters in Email Communication
It Maintains Conversation Threads
“RE” helps email systems group related messages into a single conversation, making it easier to follow discussions.
It Provides Context
When recipients see “RE” in the subject line, they immediately understand that the message is connected to something previously sent.
It Improves Organization
Keeping the same subject line (with RE added automatically) ensures better tracking and clarity in professional exchanges.
“RE” in Email Marketing
In traditional email marketing campaigns sent through an email service provider (ESP), “RE” is generally not used unless the campaign is intentionally designed to look like a conversation.
Some marketers test subject lines beginning with “RE:” to increase open rates by creating a sense of familiarity. However, this approach should be used cautiously.
Risks of Using “RE:” in Campaigns
- It may feel misleading if the email is not actually a reply
- It can damage trust
- It may increase spam complaints
- It can hurt sender reputation
Modern email marketing best practices prioritize clarity and transparency over artificial tactics.
Best Practices
- Use “RE” naturally in real email replies
- Avoid adding “RE:” to marketing campaigns unless it is genuinely part of a conversation (e.g., sales follow-up emails)
- Keep subject lines honest and aligned with the content
Key Takeaway
“RE” in email indicates that a message is a reply within an existing conversation. While it plays an important role in one-to-one communication, it should be used thoughtfully in marketing contexts to maintain trust and transparency.