When your email app shows yesterday's messages, or a message you saw on your laptop never appears on your phone, the cause is usually a sync interruption between the app and the mail server. The good news is that the mail itself is usually safe on the server. This guide helps you work out where the break is and fix it, starting with the easiest checks.
First, check whether the messages exist on the server
Before changing any settings, open your email provider's website (Gmail, Outlook.com, Yahoo, iCloud Mail, or your work webmail) in a browser and sign in. Look for the missing messages there.
- Messages are in webmail but not in your app: the problem is a sync issue on that device or app. Continue with the fixes below.
- Messages are not in webmail either: they may be in spam, archive, another folder, or filtered by a rule. Skip to the section on filters and folders.
- You can't sign in to webmail: the account itself may have a password, security, or storage problem. Resolve that first.
This test saves a lot of time. Reinstalling an app won't help if a rule has been moving mail somewhere you aren't looking.
Common reasons email stops syncing
Most cases come down to a short list: no or unstable internet connection, sync switched off for the account, battery or data-saving restrictions that stop background updates, an expired sign-in after a password change, a full mailbox, or an app that is stuck. On desktop Outlook, "Work Offline" mode is another common culprit.
Fix 1: Refresh manually and confirm your connection
Pull down on the inbox (or press the refresh or Send/Receive button) and see whether anything arrives. Then confirm the device really has internet access by loading a web page. If you are on Wi-Fi, try mobile data briefly, or the reverse. Some networks, including public and workplace Wi-Fi, block email connections even when web browsing works.
Restarting the device is worth doing here. It's quick and clears many stuck background processes.
Fix 2: Make sure sync is turned on for that account
Mail apps let you control sync per account, and an update or a past tap can leave it off. Exact menu names vary by version, but these are the usual places to look:
- Gmail app on Android: open the menu, go to Settings, choose your account, and make sure Sync Gmail is on. Also check the "Days of mail to sync" setting, since older messages won't appear if the window is short.
- Android system settings: look under Settings, then Accounts (sometimes "Passwords and accounts"), select the account, and confirm account sync is enabled.
- iPhone or iPad Mail: go to Settings, then Mail, then Accounts. Open the account and check that Mail is toggled on. Look at Fetch New Data (or the equivalent) and any "Mail Days to Sync" option.
Turning the sync toggle off and on again can prompt a fresh connection. It doesn't delete server-side email for IMAP, Exchange, or Gmail accounts.
Fix 3: Check battery, background, and data-saver limits
If new mail only appears when you open the app, background activity is probably restricted. This is especially common on phones set to save power.
- iPhone: Low Power Mode reduces background mail fetching. Also check that Background App Refresh isn't disabled for your mail app.
- Android: battery optimization, "sleeping apps," and Data Saver can all delay or block sync. Set your mail app to unrestricted or allow background data, if your phone offers that option.
Also be aware that "Fetch" schedules, where used, check for mail at intervals rather than instantly. A delay of several minutes can be a setting, not a fault.
Fix 4: Sign in again after a password or security change
If you recently changed your password, turned on two-step verification, or got a security alert, the app may have lost permission to connect. Most apps will show a prompt asking you to sign in again. Do that rather than ignoring it.
Be careful with older or third-party mail apps. Providers such as Google and Microsoft have moved away from simple password sign-in toward modern sign-in methods, so an old app or manually configured account may stop working even though your password is fine. If that happens, use the provider's own app, or add the account using the provider's recommended option in your mail app instead of typing server settings by hand. Don't weaken your account's security just to make an old app work.
Fix 5: Check for a full mailbox
If your mailbox is out of storage, incoming mail may bounce or stop arriving. With Google accounts, storage is shared across Gmail, Drive, and Photos, so a full Drive can affect email. Check your provider's storage page, then delete large attachments, empty Trash and Spam, or buy more space if needed.
Remember that deleted mail may sit in Trash and still count against your quota until it is emptied. Make sure you really don't need those messages first.
Fix 6: Look for filters, folders, and tabs
If the mail isn't in webmail's inbox either, check Spam/Junk, Archive, Trash, and any custom folders. Gmail's Promotions and Updates tabs and Outlook's Focused/Other split can also hide messages. Then review your rules or filters, since an old one may be forwarding, archiving, or deleting certain senders.
With IMAP accounts, some mail apps only show folders you've subscribed to. If a folder such as Sent or Archive looks stale, check the app's folder or mailbox settings and make sure it is enabled for syncing.
Fix 7: Understand IMAP versus POP
IMAP keeps your mail on the server and mirrors it on each device, so devices stay in step. POP downloads messages to one device and may remove them from the server, depending on settings. If you use POP on more than one device, they will look different from each other, and that is expected behavior, not a bug. Switching to IMAP, or to your provider's standard account type, is usually the better setup if you use a phone and a computer. Don't delete a POP account without confirming that its messages are backed up, because local copies may be the only ones.
Fix 8: Desktop Outlook-specific checks
In Outlook for Windows, check the Send/Receive tab and make sure Work Offline isn't highlighted. Look at the status bar for "Disconnected" or "Trying to connect." Starting Outlook in safe mode can show whether an add-in is interfering.
If the problem persists, Outlook's repair tool or recreating the profile can help. Rebuilding the local data file is a more advanced step. For Exchange, Microsoft 365, and IMAP accounts the server copy remains, but items stored only locally (such as POP data or a standalone PST file) could be lost, so back those up first.
Last resort: remove and re-add the account
If nothing else works, removing the account and adding it again forces a clean setup. Before you do this, confirm in webmail that your messages are on the server, and note any settings your work or school IT department gave you. For IMAP, Exchange, and Gmail accounts, the mail stays on the server, though local drafts or offline items may not.
When to contact support
If webmail works but one app fails after every fix, try a different mail app to isolate the cause. If webmail itself is missing messages, or you suspect your account was accessed by someone else, contact your email provider or your organization's IT team. For work or school accounts, a policy or security setting you can't see may be responsible.
What to do next
Start with the webmail check, then work through connection, sync toggles, background limits, and sign-in. Those cover most outdated-inbox cases. Save the remove-and-re-add step for last, and only after you know your mail is safely stored on the server.