Outlook.com Not Working? Common Fixes

Outlook problems fall into a handful of shapes: you cannot get in, mail is not arriving, mail will not send, or messages you know exist are nowhere to be found. This guide works through each in the order they are actually likely — starting with the one that does real, permanent damage.

Mail is not arriving

Your storage is full — and this one bounces mail

Check this first, because it is the most consequential and the least obvious.

Microsoft storage is unified. Your mailbox shares a quota with OneDrive and other Microsoft services, which means a OneDrive full of photos and documents can stop your email working entirely — with nothing in the mail interface to suggest why.

And Outlook does not simply hold messages until there is room. Microsoft's own guidance states that when storage is full, mail sent to you is bounced back to the sender and is unrecoverable. Those messages are not waiting somewhere. They are gone, and the only way to get them is to ask the sender to send again.

That makes this genuinely urgent rather than merely annoying. To check and fix:

• Open your storage page and look at the whole Microsoft storage bar — not just email. If any part shows as full, mail stays blocked.

• Empty Deleted Items and Junk; both still count.

• Delete or move large attachments. OneDrive and Photos are usually the real culprits rather than email.

• Or buy more storage, which is often the sensible answer on an account that matters.

One quirk worth knowing: storage sometimes continues to show as full even after you free space or buy more. The documented workaround is to delete emails with attachments over 10 MB, then sign out and sign back in so the figure recalculates. If it still shows full when it plainly is not, that is worth raising with Microsoft support — it is a known condition rather than something you have done wrong.

Check the Other tab

Focused Inbox splits your mail in two. Anything Outlook judges less important goes to Other rather than Focused, and if you have never noticed the tab, mail can sit there for weeks looking very much like it never arrived.

Check Other before concluding anything is missing. If the split does not suit you, Focused Inbox can be switched off entirely from the View settings, putting everything back in one place.

Check Junk, and check what you have blocked

Open Settings, then Mail, then Junk email. Two lists matter there: blocked senders, and blocked domains.

One specific trap is worth naming. Microsoft has acknowledged that blocking a single Gmail sender could accidentally add the entire gmail.com domain to your blocked list — silently cutting off every Gmail user you know. If you are not hearing from anyone on Gmail, look for gmail.com in that list and remove it.

While you are there, add important senders to Safe senders so they are never filtered again.

Check your rules and Sweep

Rules run before you see a message and can move, delete or forward it silently. A rule written years ago for one newsletter can quietly swallow anything matching a pattern you have long forgotten.

Outlook also has Sweep, which is easy to overlook because it is not in the same place as rules. Sweep can be set to delete or archive mail from a sender automatically and on an ongoing basis. If mail from one particular person keeps disappearing, check Sweep as well as rules.

Check forwarding

If forwarding is switched on and set not to keep a copy, your mail arrives and immediately leaves. Worth checking on any account you did not set up yourself, or one someone else has had access to.

Mail will not send

Sending and receiving are configured separately, so one can fail while the other works perfectly.

• Check storage again. A full account blocks sending as well as receiving.

• In a mail client, it is almost always authentication. Microsoft retired basic authentication for Outlook.com, so a client that asks for your password in its own dialogue box will be refused no matter what you type. Our security guide covers this, and the SMTP settings page has the server details.

• Check the attachment size. Outlook caps attachments and will offer a OneDrive link instead.

• Check for a temporary block. Microsoft limits sending volume to contain compromised accounts, and unusual activity can trigger a hold that clears on its own.

You cannot sign in

That is its own subject. Our guide to signing in to Outlook covers passkey prompts, verification codes and the specific errors — and if the password itself is gone, start with how to reset your password.

One cause specific to this: Microsoft may temporarily block an account after unusual sign-in activity. That is a security measure rather than a fault, and the unblock process is part of the sign-in flow.

One device is not syncing

If Outlook works in a browser but a phone or tablet is stuck, the problem is that device rather than the account.

Microsoft's own suggestion is to remove the partnership between the device and your mailbox, then add the account again. That clears a stale sync state and resolves a surprising share of cases where one device disagrees with everything else.

Before that, try the simpler checks: confirm the account is not paused in the app's settings, and confirm the app is current — an outdated client may be failing authentication rather than syncing.

Outlook is slow, blank, or will not load

Try the web interface in a private window first. That single test separates a browser problem from an account problem.

• Works in private browsing: the cause is an extension or stale cookies. Disable extensions — ad blockers and privacy tools most often — then clear cookies for microsoft.com and live.com.

• Fails there too: try another browser or device. Failing everywhere means it is not local.

Is Outlook.com actually down?

Sometimes the problem genuinely is not yours. Microsoft publishes a service status page showing current disruptions. If Outlook.com is listed as affected, there is nothing to fix at your end — and no settings worth changing while you wait, which is worth knowing before you start altering things that were working.

Narrowing it down

Rather than trying fixes at random, answer these first:

• Does it fail everywhere, or on one device? One device means a client or sync problem. Everywhere means the account.

• Can you send but not receive, or the reverse? That alone eliminates half the possibilities.

• Is it one sender, or everyone? One sender points at a block, a rule or Sweep. Everyone points at storage.

• Did it stop suddenly or gradually? Sudden suggests a change — a password reset, a new rule, an update. Gradual suggests storage filling up.

Two minutes on those questions beats an hour of changing settings, and avoids the common trap of fixing something that was never broken.