Email deliverability tools
The same checks Peakflow runs against every sending account, every night — available free, with no sign-up. Each one tells you what is wrong and what to publish to fix it.
Deliverability check
One graded report for your sending domain: SPF, DKIM, DMARC, MX, BIMI, MTA-STS, reverse DNS and blocklists.
Counts your SPF DNS lookups against the RFC limit of 10 — the most common way SPF silently fails while every other checker shows a green tick.
OpenSPF checker & generator
Check an existing SPF record or build a new one from your mail providers.
Shows the DNS lookup cost of every mechanism, so you can see which include is about to break your record.
OpenDMARC checker & generator
Read your DMARC policy, or generate one with a safe rollout path.
Warns when a record has no rua= address — without reports, DMARC gives you no visibility at all.
OpenDKIM checker
Find the DKIM key for a domain, with or without knowing the selector.
Probes 25 provider selectors and follows CNAME delegation, so it finds keys that single-selector checkers report as missing.
OpenMX & reverse DNS lookup
See which servers handle mail for a domain, and whether their reverse DNS is valid.
Checks that reverse DNS is forward-confirmed, not merely present — an unconfirmed PTR is a common cause of silent rejection at Microsoft.
OpenBlocklist check
Check your mail server IPs against several major blocklists.
Tells you which lists actually answered. A list we could not query is reported as inconclusive rather than counted as clean.
OpenEmail header analyzer
Paste raw headers to trace delivery and see why authentication passed or failed.
Reports DMARC alignment, not just pass or fail — it catches the case where SPF passed for your bounce domain and DMARC failed anyway.
Runs in your browser
OpenSpam content checker
Score a draft before you send it and see which parts read as bulk mail.
Tuned for cold outreach rather than newsletters, and your draft never leaves your browser.
Runs in your browser
OpenEmail signature generator
Build a clean HTML signature with a plain-text alternative.
Deliberately image-free and tracker-free: remote images in a signature are a common reason a plain business email gets flagged.
Runs in your browser
OpenThese checks, running continuously
A one-off check tells you where you stand today. Peakflow runs these against every sending mailbox on a schedule, warms new mailboxes before they send, and pauses a campaign when an account's reputation starts to slip.
See it in your inbox