Outlook Support and Fixes

Why Outlook breaks

Outlook sits on top of several layers: your Windows or macOS account, a mail profile, a local cache file, Microsoft 365 sign-in tokens, and DNS records for your domain. When any layer is wrong, Outlook is where you notice it. That is why a quick reinstall often does not help: the problem is somewhere else.

dijitul support works through each layer in order and fixes the actual cause. For the wider picture of email and Microsoft 365, see email support and Microsoft 365 support, or our main IT support page.

Outlook keeps asking for a password

This is the most common Outlook complaint we see. Typical causes are:

• Stale credentials in Windows Credential Manager from an old password. We remove the cached Office and MicrosoftOffice16 entries so Outlook signs in fresh.
• A broken Entra ID registration on the PC, so modern authentication cannot get a token. Checking the device under Access work or school usually shows this.
• An old profile set up for Basic Authentication, which Microsoft has switched off in Exchange Online. The profile needs rebuilding for modern authentication.
• An expired password or MFA requirement the user has not completed in a browser.

Testing a sign-in at outlook.office.com first tells us whether the account or the device is at fault.

Profiles, OST files and Autodiscover

Corrupt or oversized OST

Classic Outlook keeps a local copy of your mailbox in an .ost file. If it gets very large or corrupted, Outlook slows, search fails and items go missing. Reducing the Cached Exchange Mode window to 12 months, or rebuilding the OST, normally fixes it. Your mail is safe in Exchange Online while we do this.

Autodiscover pointing the wrong way

Outlook uses Autodiscover to find your mail server. If your domain still has an old autodiscover record pointing at a previous host, Outlook may try to connect there first. For Microsoft 365 the CNAME should point to autodiscover.outlook.com. See domain and DNS support.

Missing shared mailboxes

Shared mailboxes appear automatically through auto-mapping when Full Access is granted. If permissions were added through a group, auto-mapping does not apply and the mailbox has to be added manually.

New Outlook, classic Outlook and Outlook for Mac

Microsoft is moving Windows users to the new Outlook for Windows, which is built on Outlook on the web. It handles some things differently: it does not support PST files in the same way, some COM add-ins do not work, and offline storage is limited. If a toggle moved your team to new Outlook and something stopped working, we can switch you back to classic Outlook or fix the gap.

Outlook for Mac has its own quirks, such as the legacy and new interfaces and keychain password prompts. See Mac support.

Quick checks before you call

If you want to try something yourself first, these checks are safe and often tell us a lot:

1. Try Outlook on the web at outlook.office.com. If mail is there, your mailbox is fine and the problem is on your device.
2. Check the status bar at the bottom of classic Outlook. If it says Working Offline, turn it off on the Send and Receive tab.
3. Start Outlook in safe mode by holding Ctrl while opening it. If it works, a faulty add-in is likely.
4. Run an Office Quick Repair from Settings, Apps, Microsoft 365, Modify.

If none of that helps, tell us what you saw at each step and we will pick it up from there.

Cost of Outlook support

Most Outlook problems are fixed in one remote session. We charge £45 an hour + VAT with a 30-minute minimum, then 15-minute blocks. If your team has regular Outlook and Microsoft 365 questions, the Complete plan at £99 a month + VAT includes 3 hours of work and an IT helpdesk. If your problem is mail landing in junk rather than Outlook itself, see email deliverability. Ready to fix it? Get in touch.

What it costs

Support plans from £25 a month + VAT, or £45 an hour + VAT for one-off fixes. Pick a plan if you want it looked after every month, or pay by the hour for a one-off job.

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