You can edit a Gmail subject line only before you send the message
Gmail does not let you change the subject line after you hit Send. The subject field is editable only while the message is still in your drafts or open in the compose window. Once the email leaves your outbox, the subject is locked. If you need to correct a subject line on a message you already sent, your only option is to send a new message with the correct subject and ask the recipient to disregard the first one.
If you catch the mistake before sending, the fix takes seconds. If the message is already in your Sent folder, you will need to start over with a fresh email.
Key Takeaways
- The subject line can only be changed while the message is in your compose window or saved as a draft — not after you send it.
- To edit a draft, open it from your Drafts folder, click the subject field, and type the new subject.
- If you sent the message with the wrong subject, you cannot change it; you must send a follow-up email with the correct subject instead.
- Gmail auto-saves drafts every few seconds, so you can close and reopen a message and still edit the subject before sending.
How to change the subject line in an unsent draft
Open your Drafts folder by clicking the three horizontal lines (menu icon) on the left side of Gmail, then select Drafts. Find the message you want to edit and click it to open the full compose window.
At the top of the compose area, you will see the subject field with your current subject line. Click directly on the subject text and it will become editable. Delete the old subject and type the new one. Gmail saves your change automatically within a few seconds — you do not need to click a save button. When you are ready, click Send.
How to change the subject line before sending a new message
When you start a new message by clicking Compose, the subject field appears below the "To" line. Type or paste your subject there. If you need to change it before sending, simply click the subject field again and edit the text. You can do this as many times as you want while the message is still open.
If you close the compose window without sending, Gmail saves the message as a draft. You can return to it later, open it from your Drafts folder, and edit the subject again before you send.
What to do if you already sent the message with the wrong subject
Once an email is sent, Gmail does not provide a way to edit or unsend it (though Gmail does have an Undo Send feature that works for a few seconds after you click Send — if you notice the mistake immediately, look for the "Undo" link that appears at the bottom of the screen). If you miss that window, the sent message cannot be changed.
The standard approach is to send a new email to the same recipient with the correct subject line. In the body, briefly explain that you sent a previous message with an incorrect subject and ask them to refer to the new message instead. This is clearer than trying to edit the original after the fact.
Why Gmail locks the subject line after sending
Email systems, including Gmail, treat the subject line as part of the message header — the metadata that routes and organizes the email. Once a message is delivered to a recipient's inbox, changing the subject would create confusion about which conversation thread it belongs to and could break the threading that groups related messages together.
This is a limitation of email itself, not just Gmail. No major email provider allows you to change a subject line after sending because doing so would disrupt how email clients organize and display conversations.
Using the Undo Send feature to catch mistakes fast
Gmail's Undo Send feature gives you a short window — usually 5 to 30 seconds, depending on your settings — to take back a message after you click Send. To turn this on, go to Gmail Settings (the gear icon in the top right), click See All Settings, then go to the General tab. Scroll down to Undo Send and check the box next to it. You can choose how many seconds you want the undo window to last.
If you enable this feature and notice a subject line error right after sending, click the Undo link that appears at the bottom of the screen. The message returns to your compose window, where you can fix the subject and send it again.
Frequently Asked Questions
Can I change the subject line on an email someone sent me?
No. You can only change the subject line on messages you compose yourself, either before or after you receive a reply. If you want to change how a conversation appears in your inbox, you can create a label or filter, but the original subject line in the email thread cannot be edited.
What if I sent the message to the wrong person but with the right subject?
You cannot recall or delete a message from someone else's inbox. Send a follow-up message to the correct recipient with the information they need, and send a separate message to the person who received it by mistake, asking them to disregard the first message.
Does Gmail have a way to edit sent messages at all?
Gmail does not allow editing of sent messages in any form — not the subject, body, or attachments. The only exception is the Undo Send feature, which works for a few seconds after you click Send and returns the message to your drafts so you can edit it before sending again.
If I save a message as a draft, can I change the subject later?
Yes. Drafts remain fully editable until you send them. Open the draft from your Drafts folder, click the subject field, make your changes, and send. Gmail saves your edits automatically.