What to do when your business email stops working

Start with the browser test, because it splits the problem in half

Most wasted time on email problems comes from fixing the wrong layer. Someone rebuilds an Outlook profile for an hour when the actual issue was a DNS record changed by whoever last touched the website.

The browser test settles it in thirty seconds. Sign in to your mail through a browser on any device. Webmail talks straight to the mail service and skips the app, the profile and the local cache entirely.

1. 1Webmail works, the app does not → the problem is on that device. Go to the app section below.
2. 2Webmail fails to sign in → the problem is the account. Go to the account section.
3. 3Webmail works, you can send but nothing arrives from outside → the problem is the domain. Go to the domain section.

If it is the mail app on one device

This is the easiest case, because everyone else is unaffected and your mail is safe on the server.

1. 1Close the mail app completely and reopen it. Not minimise — quit.
2. 2Check whether the app is in offline mode. In Outlook this is Send/Receive → Work Offline, and it gets switched on by accident more often than anyone admits.
3. 3Confirm the device is actually online by loading any website.
4. 4Check whether the mailbox is full. A full mailbox stops receiving while still letting you read old mail, which is exactly what makes it confusing.
5. 5If one device is affected and others are fine, remove and re-add the account on that device rather than rebuilding anything else.

If it is the account

When webmail itself will not let you in, no amount of app configuration helps. Something has changed about the account.

1. 1Read the error precisely. "Incorrect password" and "your account has been locked" are different problems with different fixes.
2. 2Check whether the licence or subscription is still paid. A lapsed subscription disables mailboxes, and the warning emails about it go to the mailbox that just got disabled.
3. 3Check whether multi-factor authentication was recently enrolled, or the person changed phone. A new phone without the authenticator app moved across locks people out cleanly.
4. 4Have an administrator confirm the account is still enabled. Offboarding somebody sometimes disables the wrong account.

If it is the domain — the one that takes days to notice

This is the case worth knowing about, because it is quiet. You can send mail perfectly well while nothing reaches you, and you only find out when a customer says they never got a reply.

It almost always follows a change: a new website, a host migration, a DNS move, a domain renewal handled by somebody else. The MX records — the records that tell the world where your mail lives — did not come across with the rest.

1. 1Ask what changed in the last week. Website, hosting, DNS, domain registrar. There is nearly always something.
2. 2Check your MX records with any public MX lookup tool. They should point at your mail provider, not at your web host.
3. 3Check SPF, DKIM and DMARC while you are there. If these are missing or wrong, your mail still sends but lands in spam — a different symptom, same root cause.
4. 4After correcting a DNS record, expect a wait. Changes take time to spread, and that wait is normal rather than a sign the fix failed.