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Inbox vs spam tests

Embed unique signals in new outreach and probe Gmail, Outlook, and Yahoo to see whether mail is hitting the inbox or the spam folder.

5 min read

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Signals in mail you send Seed inboxes (the reliable spam test) Reading the results

Delivered is not the same as inbox. Receiving servers accept a message, then file it in the inbox, Promotions, or spam. FlareMail tests new outreach (not ordinary replies): it embeds unique signals, copies the message to your seed inboxes, and shows a health badge on that Sent-folder copy.

Signals in mail you send

New mail that is not a reply gets a unique token in an X-Flare-Signal header. HTML mail also gets a 1×1 pixel hosted on the FlareMail Worker. Text-only mail stays text — FlareMail does not wrap it in HTML just to carry a pixel. Ordinary replies skip tracking so they look like conversation, not a campaign. When Gmail’s image proxy fetches that pixel, FlareMail records a Gmail inbox-correlated open. Outlook and Yahoo proxies are counted the same way.

  • Gmail / Outlook / Yahoo pixel — strong inbox signal. Those apps usually do not fetch images from spam.
  • Apple Mail Privacy Protection — ignored. Apple prefetches images even from junk, so it cannot prove inbox.
  • Spam complaint (ARF) — the recipient or provider marked the message as spam after delivery.
  • No signal — unread, images blocked, or no seeds configured. Add a seed inbox so every send is tested against Gmail/Outlook spam.

Seed inboxes (the reliable spam test)

Gmail, Outlook, and Yahoo do not auto-forward mail that landed in spam. So if a test message you send to a Gmail seed is forwarded into FlareMail, it hit the inbox — not junk. Promotions and Updates still count as inbox.

  1. Create a seed addressUse a Gmail, Outlook, or Yahoo account you control. Don’t use a real customer’s mailbox.
  2. Forward it to FlareMailIn Gmail: Settings → See all settings → Forwarding and POP/IMAP. Forward to one of your FlareMail addresses. Confirm the verification message in FlareMail.
  3. Add the seed in FlareMailOpen Settings → Inbox placement, paste the Gmail/Outlook/Yahoo address, and save. After that, new outreach is copied to the seed (hidden Bcc) and tested automatically. Replies are not copied.
  4. Optional dedicated probeClick Test to send a standalone probe from your domain. Setup Doctor shows Inbox, Waiting, or Missing / spam. You do not need this for ordinary mail — Sent already shows health per message.

Reading the results

  • Inbox — the forwarded seed copy arrived, the recipient confirmed the link, or Gmail/Outlook/Yahoo fetched the pixel.
  • Checking — this send was copied to your seeds; forwarding can take a few minutes (up to ~45).
  • Spam likely — no seed forward or inbox pixel before the timeout, or a spam complaint.
  • Sent-folder badge — every Sent row and the message preview show that copy’s health. Recipients never see the seed Bcc.