A quiet inbox can hide a delivery problem. If a customer says they never received your quote, it is worth checking the journey before assuming they lost interest. Rewriting the subject line alone may not address the cause.
Start with an actual example
Choose a recent message that went missing. Note the sender, recipient, approximate time, and which application sent it. Ask whether it landed in spam, bounced, or never appeared. Those are different symptoms. Keep any bounce message intact rather than forwarding only the error number. Compare a normal staff email with a website notification: they may use different sending services.
Check the business behind the address
Make a list of everything that sends using your domain: your mailbox provider, invoicing tool, booking system, website, and newsletter platform. An old tool can be overlooked when a domain changes. Email authentication helps receivers check whether a sender is authorised; Google recommends SPF, DKIM, and DMARC. Authentication is a foundation, not a promise of inbox placement.
Make the next test useful
Avoid changing several settings at once. Have the configuration reviewed, record the change, and compare results using the same message type. Test replies as well as new messages. If the issue affects only one organisation, that recipient’s administrator may need to investigate. Keep customer follow-up separate: a phone call can confirm receipt while the technical work continues.
Use the result to choose the next check
A rejection and a message accepted into spam need different investigations. For a rejected message, keep the full diagnostic and ask the sending provider which system refused it. For a message found in spam, ask the email administrator to inspect the original headers and authentication results. A passing authentication result does not prove inbox placement. Compare the affected sending tool with normal staff email; they may use different infrastructure. If the problem is limited to one customer organisation, share the timestamp, destination and message identifier with its administrator through an agreed channel. A delivery log can show a system event, but it cannot establish that someone read the quote.
Make it actionable
Your next steps
- Save one missing-message example and the full rejection diagnostic if present.
- List the tool that sent it and compare normal staff email.
- Record the destination, time zone and available message identifier.
- Ask for a review before changing domain records or filtering rules.
Official reference
Google: Email sender guidelines
Guide date: September 29, 2026. Product features and requirements can change. The business checklists above are practical suggestions from Cyber Bounds.
Put the next step into practice
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