Cold email subject line generator (no AI)
A cold email subject line generator turns what your email is about into short subject lines you can test. Enter the topic, the result you help with and, if you have one, a reason to write now. You get question, personal, trigger, short and outcome lines, each checked against SpamAssassin's subject rules and Google's sender guidelines, and flagged if a phone would cut it off.
Sample result
14 subject lines about outbound bounce rates, none tripping the tester's filter rules.
- Subject lines
- 14
- Styles
- Question, personal, short, outcome
- Shortest
- Quick idea
What this means for you
Pick two and A/B test them to see which gets more opens.
- 22 patterns across five styles
- Skips patterns missing a slot
- Every line run through the tester's rules
- Download the list as CSV
- Subject lines
- No AI
- CSV
By SimpleVerifier Team · Last updated · Runs in your browser; nothing you paste is sent to us
How do I generate subject lines for a cold email?
- Describe the email: what it's about, the result you help with and, optionally, who they are and why you're writing now.
- Keep the merge tags for first name and company, or type real values to preview one recipient.
- Press Generate subject lines. Clean lines that fit a phone screen come first; flagged ones say which rule they hit.
- Filter by style, copy the two or three you like best and A/B test them on a small batch before the full send.
Example
- You enter
- Topic: outbound bounce rates, with the
{{first_name}}and{{company}}merge tags kept. - You get
- 14 subject lines across question, personal, short and outcome styles, such as “Question about outbound bounce rates” (36 characters), none tripping the subject line tester's filter rules.
- Limits
- Each field takes up to 80 characters; fixed patterns, no AI, runs in your browser.
What is a good cold email subject line?
A good cold email subject line is short, specific and honest about what's inside, so it reads like a note from a person rather than a campaign. In practice that means a few words, often a question or a reference to the recipient's company or a recent event, in sentence case with no hype. The generator's patterns follow that: "Question about outbound bounce rates", "Idea for {{companyName}}", "Saw the new SDR team".
Two rules are firm rather than taste. Google's email sender guidelines say not to use deceptive subjects, and specifically not to start with Re: or Fwd: unless the message really is a reply or forward, so the generator never adds them. And several SpamAssassin rules score subject lines directly, such as all capitals (SpamAssassin's published rule list); every generated line is run through the same rules as our subject line tester.
How do I write a cold email subject line?
Start from the reason the email exists, not from a formula. Name the topic in the recipient's words ("onboarding", not "our customer success platform"), and if there's a genuine trigger, a funding round, a hire, a launch, use it: a subject that refers to something real about them is the hardest to mistake for a blast. Then cut words until it still makes sense.
Put the specific word first, because phones truncate from the right. The generator measures each line against the subject width the Gmail app shows on a 390px phone, the same estimate the subject line tester uses, and marks lines likely to be cut. Real truncation depends on the app and text size, so treat it as a guide.
What should a cold email subject line be for a job or internship?
The same principles apply: say what it's about and make it about them. Put the role or team as the topic ("the analyst role", "your research on soil carbon") and something you can offer as the result ("a portfolio for the design role"), and the question and personal patterns will produce lines like "Question about the analyst role". Keep a real name in place of the merge tag when you're writing one email by hand.
Why doesn't this use AI?
So the output is predictable, private and costs nothing per use. Each line is a fixed pattern filled with your own words; nothing is sent to a server or a language model, and a pattern that needs a slot you left empty is skipped rather than padded with invented claims. Our template-based cold email generator works the same way for the body.
Template generator or AI generator?
| This generator | AI subject line tools | |
|---|---|---|
| Where your offer goes | Stays in your browser | Sent to a model provider |
| Same input, same output | Yes | No |
| Spam-rule check on each line | Yes | Rarely |
| Invents claims or numbers | Never | Can |
| Variety | 22 fixed patterns | Unlimited |
Who uses this tool, and for what?
- SDRs and founders
- Get a dozen honest subject lines for a new sequence in a minute, then A/B test the best two on a small batch.
- Agencies
- Draft subject options for a client campaign with merge tags already in place for Instantly, Smartlead or lemlist.
- Job seekers
- Turn the role and your angle into short, specific lines for networking or cold applications.
- Recruiters
- Write candidate outreach subjects that name the role and the company without sounding like a mass mailing.
What can’t this tool tell you?
- It can't predict open rates. Opens depend on the sender, the list and the inbox, and Apple Mail Privacy Protection inflates measured opens.
- The rule check covers subject-level SpamAssassin and Google rules; filters also weigh your domain's reputation and the body.
- Phone width is estimated for the Gmail app at default text size; other apps and settings cut at different points.
- Patterns are in English and assume noun phrases; awkward input gives awkward lines, so edit before you send.
Common questions
- What is a good cold email subject line?
- A short, specific line that says what the email is about, ideally referring to the recipient's company, role or a recent event, in sentence case with no hype or fake Re: prefix.
- What to put in the subject line of a cold email?
- The topic in the recipient's words, or a genuine reason you're writing now. "Question about {{companyName}}'s onboarding" tells them what to expect; "Quick win inside!" doesn't.
- What should a cold email subject line be?
- Short, specific and accurate: usually a few words, readable on a phone. No mail app guarantees a length, so put the specific word first; the generator flags lines a phone is likely to cut.
- What is Re in an email subject line?
- It marks a reply, so only use it on a real one. Google's sender guidelines say not to use Re: or Fwd: to make a message look like part of a conversation, and recipients who notice tend to mark it as spam.
- How to cold email for a job: what subject line?
- Name the role or team and your angle, such as "Question about the analyst role" or "Portfolio for the design role". Use the hiring manager's real name rather than a merge tag.
- What is the best subject line for a sales email?
- There isn't one line that wins everywhere; the best is specific to the recipient and honest about the email. Generate several here, keep the clean ones and A/B test two on a small batch.
Sources
Authentication and capacity are half of deliverability.
The other half is who you send to. Every hard bounce counts against the domain and inboxes you are sending from, and nothing in DNS can tell you which addresses on your list are dead.
- Bulk verification with real SMTP mailbox checks
- Hard bounces removed before a send, not discovered after
- Catch-all, disposable and role detection on every row
One plan, cancel anytime, no contract. Sign in with Google and your first 100 email checks are free, no card. The free tools stay free either way.