Can a spam checker tell me if my email will reach the inbox?

No, and any tool that claims to is guessing. Inbox placement depends on your sending history, your domain reputation, and how the specific recipient has treated your mail before, none of which is visible from the content. What a content checker can tell you is which problems are in the message itself, which is the part you control.

What does CAN-SPAM actually require in an email?

A truthful From and subject line, a clear way to opt out that keeps working for at least 30 days, opt-out requests honoured within 10 business days, a valid physical postal address, and identification as an advertisement when the recipient did not opt in. Penalties run to $53,088 per individual message, and each email in a campaign counts separately.

Why is an image-only email a problem?

Most clients block images by default, so a reader opening it sees an empty message. It is also the oldest technique for hiding text from a filter that cannot read pictures, so filters treat an email with no text as evidence of exactly that. Write enough text that the message still makes sense with images turned off.

Do spam words still matter?

Far less than the long word lists suggest. Modern filters are statistical, so a single word moves almost nothing. The phrases that still carry weight are the ones that co-occur with actual fraud: prize claims, income promises, absolute guarantees and payment-fraud language. A list of three hundred forbidden words is a sign the tool does not know what it is measuring.

Free email spam checker

Two kinds of problem live in an email: the ones that break the law, and the ones that make a filter suspicious. This finds both and names them.

Subject lineThe email (paste the HTML or the plain text)This is a commercial message

This runs entirely in your browser. Nothing you paste is sent anywhere.

What the score is, and is not

It is a count of problems in the content, weighted by how badly each one hurts. It is not a prediction about the inbox, because nobody outside the receiver can make one: placement depends on your sending history and on how that particular reader has treated your mail before. A tool that prints “you will reach the inbox” is selling confidence it does not have.

The two that are law, not advice

A working unsubscribe. Required in every commercial message, it has to keep working for 30 days after the send, and requests must be honoured within 10 business days. Gmail and Yahoo additionally require a one-click List-Unsubscribe header from bulk senders.
A physical postal address. Also required in every commercial message. A PO box or a registered agent address satisfies it, so you do not have to publish where you live.

Penalties run to $53,088 per message, and each email in a campaign counts separately, which is what makes this the cheapest thing on the page to fix.

The content signals that still matter

An image with no text. Images are blocked by default, so the reader sees nothing, and filters read it as text being hidden from them.
A link to a bare IP address. Treated as hostile almost without exception.
A public URL shortener. Its reputation is shared with everyone else who used it that week, including the people you would rather not share with.
Two words and a link. That is the shape of a compromised account sending to a stolen address book, and filters know the shape.

These are the same checks Action BeeMail runs before a campaign goes out. Also free: the subject line tester, the CAN-SPAM footer generator and the SPF, DKIM and DMARC checker.