Email signatures and HTML email checks

Spam, Subject Lines and Headers

These tools look at what happens to an email after you write it. Check the content against spam-filter rules, preview the subject line and preheader in an inbox, and read the route and authentication results in headers or DMARC reports.

Tools in this group

  • DMARC Report Analyzer — Open one or more DMARC aggregate reports to see who sends mail for your domain and whether it passes SPF, DKIM and DMARC.
  • Email Header Analyzer — Paste the raw headers of an email, or open an .eml file, to see its route, delays and authentication results in plain tables.
  • Email Spam Checker (Content Check) — Paste the subject and body of your email, or open an .eml file, to see which spam-filter rules it matches and what to fix.
  • Gmail Attachment Size Limit: Check Gmail, Outlook and Yahoo — Type or pick your attachments to see whether they fit the Gmail, Outlook.com, Yahoo and Microsoft 365 limits once email has encoded them.
  • Spam Word Checker — Paste your email text to highlight the words and phrases that spam-filter rules score, with plainer alternatives.