Email Not Sending or Receiving? Triage by Cause

Email problems can have many causes, but you can narrow things down in the first 30 seconds by splitting the situation into two questions: ①Can you not send, or are you not receiving (nothing is coming in)? ②Is it happening to you alone, or to everyone in the office? Answer these two questions first, then use the table below to narrow down the cause.

- Take a screenshot of the exact error message when sending fails (you'll need it no matter who you contact)
- Ask one colleague by chat or phone whether they're seeing the same problem
- Think back to anything that changed recently — a password reset, a new PC or phone set up with mail
- Check whether the problem is with one specific contact/company, or with everyone

A very common complaint is: 'Mail to Company A never arrives' or 'it always ends up in their spam folder.' This is usually related to authentication settings that the recipient's server uses to automatically judge whether your mail is legitimate — known as SPF, DKIM, and DMARC. These sound technical, but the idea is simple: SPF is a list of 'servers allowed to send mail for this domain,' DKIM is a digital seal proving the message wasn't tampered with in transit, and DMARC is the rule for what to do with mail that fails those checks (mark as spam, reject, etc.). These settings are configured on the server side that manages your domain, so if mail to a specific recipient keeps failing, the fastest fix is asking your email/hosting provider to check your SPF/DKIM/DMARC settings.

If everything worked yesterday and email suddenly stopped working entirely today, a commonly overlooked cause is an expired domain or mail server contract. Domains typically auto-renew annually, but renewal can silently fail due to an expired credit card or a staff change. Check your provider's account page or billing emails for the contract status. If you can't reach the agency or vendor that manages this for you, see What to Do When You Can't Reach a Vendor for next steps.

- Sent messages appear in your Sent folder that you never wrote
- A business contact tells you they received a suspicious email "from you"
- You can't log in even though you never changed your password
- You receive login notifications from an unusual location or from overseas

If any of these signs appear, this may not be a simple glitch but an account takeover or impersonation attack. Stopping further damage takes priority over diagnosing the cause. See Emergency Response to a Ransomware Incident and First Security Steps for Small Businesses, and promptly change your password, enable multi-factor authentication, and warn your business contacts.