Email deliverability tools: check your setup before you send

Spam and content checker

Scores a draft before you send it. Every rule that fires adds points to a score out of 10, and each finding comes with a plain-language fix.

• Spam-trigger words and shouting in the subject and body
• Missing unsubscribe link or plain-text version
• Image-to-text balance, link shorteners and risky domains
• Free-mail From addresses, attachments and merge-tag mistakes

A guide in the spirit of SpamAssassin's content rules. It cannot see your sending reputation or the recipient's filters.

Domain health (SPF, DKIM, DMARC)

Reads your sending domain's DNS live and tells you what is missing or wrong. Nothing is guessed.

• MX, SPF, DKIM, DMARC records
• BIMI, MTA-STS and TLS-RPT
• Recognises Google, Microsoft 365, Zoho, SES, SendGrid, Mailgun, Brevo and more, and shows where to turn DKIM on

Blacklist check

Looks up your sending IP or domain on well-known DNS blocklists such as Spamhaus ZEN, SpamCop, PSBL and UCEPROTECT.

• Listed, not listed or unknown, never reported as clean when the answer was unclear
• What each listing code means and where to ask for removal

List cleaner

Looks through a category and groups the addresses that are likely to hurt you. It only reports until you confirm an action.

• Duplicate addresses
• Disposable-email domains
• Role accounts such as info@ or admin@
• Common domain typos (gmial.com and similar)
• Addresses whose domain cannot receive mail

Subject line tester

Measures a subject line and shows how it will look on a phone and on a desktop inbox, then compares two options side by side.

• Length against typical mobile and desktop cut-offs
• Emoji, capitals and punctuation
• The same subject rules the spam checker uses
• Merge tags that would come out empty

Link checker

Requests every link in your message and reports what it finds before your readers do.

• Broken links and server errors
• Redirect chains, followed hop by hop
• Link shorteners and non-HTTPS links

Inbox preview

Renders your message for a contact in a chosen category, or for a sample person, so you see the merge tags filled in exactly as a recipient would.

• Personalised subject and body
• Plain-text version generated from your HTML

SMTP tester

Walks through a connection step by step and times each one, without sending any email.

• DNS lookup, TCP connection and server greeting
• TLS or STARTTLS
• Login (AUTH)
• Shows exactly which step failed, which is usually the fastest way to fix a sender

Header analyzer

Paste the raw headers (or a whole .eml file) of a message you received and read how it travelled and whether it was authenticated.

• The route through each server and the delay at each hop
• SPF, DKIM and DMARC results
• Return-Path, From and Reply-To mismatches