How to write an email subject line
- Choose what the email is for.
- Fill in the short fields.
- Copy a subject, or check your own.
Examples
Invoice INV-0042 for ₹45,000, due 15 November, for a website redesign: the ideas include “Invoice INV-0042: ₹45,000 due 15 November” at 41 characters and “Payment reminder: invoice INV-0042 due 15 November” at 50, which a phone may cut just after the invoice number.
Casual leave from 10 to 12 November for Rahul Mehta: “Leave request: 10 to 12 November” is 32 characters, short enough for most phone inboxes, while “Casual leave request for 10 to 12 November - Rahul Mehta” is 56.
“URGENT!!! Payment pending” is a good length at 25 characters, but it's flagged three times: for capitals, for the repeated !!!, and for urgent, a word that often trips spam filters.
About this tool
A clear subject gets your email opened and found again later. Choose what the email is for, such as a meeting request, a leave request or an invoice, fill in a few details and pick from several subject lines. Then check any subject for length, capitals, punctuation, emoji and words that often trip spam filters.
Common questions
How long should a subject line be?
Phone inboxes often show only about 30 to 40 characters, so put the important words first. That's guidance rather than a rule, as every app and screen size is different.
Will a word like urgent send my email to spam?
Not on its own. Spam filters weigh the whole message, the sender and their history. The checker lists words that often appear in spam so you can choose plainer ones, but a genuine invoice or deadline is fine.
Should I put Re: on a new email?
No. Use Re: and Fwd: only on real replies and forwards. Adding them to a new email can look like a trick.
Is it free to use?
Yes. There's no sign-up, and you can use it as often as you like.
Is my text uploaded anywhere?
No. This tool runs inside your browser, so what you enter stays on your device.
Do I need to install anything?
No. It works in your browser on a computer or a phone.