Why am I not receiving emails? A step-by-step troubleshooting order

An email you're expecting hasn't arrived. Usually it did arrive and was filed somewhere you didn't look. Sometimes it was refused, and the sender holds the clue. This guide gives you the order to check things in, from the 30-second checks anyone can do to the admin tools that show exactly what happened to a message.

What should you check first?

Work through this list in order. Each step rules out a common cause before you spend time on a rarer one.

1. Ask the sender if they got a bounce. A bounce (also called a non-delivery report or NDR) is an automatic reply saying the message couldn't be delivered. Its error code usually names the cause.
2. Search every folder. Include Spam or Junk, Trash or Deleted Items, Archive, and Outlook's Other tab. In Gmail, use the search options and choose Mail & Spam & Trash (Gmail Help).
3. Check on the web. Sign in to your mailbox in a browser. If the message is there but not on your phone or desktop app, the problem is the app, not delivery.
4. Check rules, filters and blocked senders. A rule that deletes, archives or moves mail hides it silently.
5. Check forwarding. If mail is forwarded to an address you don't recognize, treat it as a possible account compromise.
6. Check your storage. A full mailbox can refuse new mail.
7. If you're the admin: trace the message in the admin console, then check MX records, then filters and blocklists.

Is it all email or just one sender?

Before you dig in, decide which pattern you're seeing. It points to very different causes.

Did the sender get a bounce message?

The bounce is the most useful piece of evidence you can get, because it comes from the server that refused the message. Ask the sender to forward it to you, or paste the error into the SMTP Error Code Lookup.

SMTP replies starting with 5 are permanent failures and those starting with 4 are temporary (RFC 5321, section 4.2). A 4xx means the sender's server will keep trying, so the message may still arrive.

No bounce at all usually means one of two things. Either the message was accepted and is in your mailbox somewhere, or it never left the sender. Ask them to check their Sent folder and Drafts.

Is the email in spam, junk, quarantine or another folder?

Spam filtering is the most common reason a real email "never arrived". Search everything before you change any settings.

• Gmail: search with Mail & Spam & Trash selected. Google notes that Trash and Spam are "permanently deleted after 30 days" (Gmail Help).
• Outlook.com: check Junk Email, the Other tab if Focused Inbox is on, Archive and Deleted Items. Microsoft says messages are removed from Junk Email "after 30 days and aren't recoverable" (Microsoft Support). Also select Filter above the message list and choose All, in case a filter view is hiding mail.
• Work email: your organization may hold suspicious mail in a quarantine that never reaches your mailbox. See what email quarantine is and how to release quarantined email in Microsoft 365.

If you find the message in Spam, mark it Not spam. Repeated false positives from one sender have a cause worth fixing, which we cover in why did this email land in spam.

Could a rule, filter or blocked sender be hiding it?

Rules run silently. A rule you made years ago, or one an attacker added, can move or delete messages before you see them.

In Gmail

Go to Settings > See all settings > Filters and Blocked Addresses. Google says to look for filters that contain Delete it or Skip Inbox (Gmail Help). Remove the sender from the blocked list if they're on it. Then open the Forwarding and POP/IMAP tab. Google warns that if your emails go to an unfamiliar address, "someone may have unauthorized access to your account." Turn that forwarding off.

If you use a desktop app with POP, make sure it isn't set to delete Gmail's copy.

In Outlook.com and Outlook on the web

Open Rules in Settings on a computer; Microsoft says rules must be viewed and edited there. Check for rules and Sweep rules that move or delete mail from the sender. Review Junk email settings for blocked senders and domains.

If you find a rule you didn't create

That's a classic sign of a compromised account: attackers hide replies and forward copies to themselves. Change your password, turn on multifactor authentication, and work through signs your email account is compromised. Admins should read malicious inbox rules and auto-forwarding.

Is your mailbox full?

A full mailbox refuses new mail, and senders get a bounce such as 552 5.2.2.

• Gmail (personal): Google gives 15 GB free, shared across Gmail, Drive and Photos. When you're over the limit, Google says "your ability to send and receive email in Gmail can be impacted" (Google One Help). Large photo backups can fill the space without you touching email.
• Microsoft 365: mailbox size depends on the license; Microsoft lists, for example, 100 GB for Business Basic and Standard user mailboxes at the time of writing (November 2026) (Microsoft Learn).

There's also a rate limit. Exchange Online accepts up to 3,600 messages per hour per mailbox, and one sender can use 33% of that. Over the limit, internet senders get an NDR and the limit "will refresh" after an hour, according to the same page. That mostly affects shared inboxes hit by a mail loop or an email bombing attack.

Clearing space fixes new mail, but anything that already bounced has to be sent again.

Are your domain's MX records correct?

If you use your own domain (you@yourcompany.com) and suddenly receive nothing, check DNS. An MX record is the DNS entry that tells other servers where to deliver mail for your domain. If it points to the wrong place, mail goes there instead, or bounces. Our guide to what an MX record is explains them in detail.

A Google Workspace domain, for example, publishes this (example):

example.com.   3600   IN   MX   1   smtp.google.com.

Common ways MX records break:

1. A website or hosting move replaced the DNS zone and dropped or changed the MX records.
2. Someone added the new provider's MX without removing the old one, so some mail goes to an old server.
3. The domain expired, and the registrar stopped answering for it.
4. A filtering service was switched off but MX still points to it.

Run an MX Lookup and compare the result with what your email provider tells you to publish. For Microsoft 365 or Google Workspace, the DNS Setup Checker compares your MX, SPF, DKIM and DMARC against their documentation. If you're changing MX on purpose, follow how to change MX records without losing email.

Is a spam filter or blocklist rejecting the sender?

Your mail server or filtering service can refuse mail before it reaches any mailbox. That happens when:

• The sender's server is on a blocklist (a DNS-based list of IP addresses known for sending spam). Check the IP from their bounce with the Blacklist Checker. Our guide to email blocklists explains how they work.
• The sender fails authentication. If their domain publishes a strict DMARC policy and their mail fails SPF and DKIM, receivers may reject it. The fix is on their side. Point them to why DMARC fails.
• An admin block list, country filter or attachment filter matched. Only an admin can see and change these.

In these cases you can't fix it from your inbox. Forward the details to whoever runs your email.

How do admins trace a missing email?

If you manage the mailbox, stop guessing and trace the message. Both big platforms keep a log of what they received and what their filters did.

Step-by-step guides: Microsoft 365 message trace and Google Workspace Email Log Search. If the platform has no record at all, the message never reached it, so check MX records and any gateway in front of it. For platform-specific checklists, see Google Workspace not receiving emails.

Microsoft also offers an automated diagnostic. Microsoft's guide to email delivery issues describes Diag: Troubleshoot Email Delivery in the Microsoft 365 admin center, where you enter the sender and recipient and select Run Tests.

Why do some emails arrive hours late instead of not at all?

A late email is usually one that was temporarily refused and retried. Some servers use greylisting, which deliberately refuses mail from unfamiliar senders the first time and accepts it on retry; see what greylisting is. RFC 5321 suggests a retry interval of at least 30 minutes and a give-up time of at least 4 to 5 days (section 4.5.4.1), so a single deferral can cost half an hour or more.

To see exactly where the time went, open the message's headers and compare the timestamps on each Received: line in the Email Header Analyzer. Microsoft 365 admins can follow Microsoft 365 email delayed: troubleshooting.

Next steps

• Today: search every folder, check rules, filters, forwarding and storage, and ask the sender for their bounce.
• If you run the domain: look up your MX records with the MX Lookup and trace the message in your admin console.
• If a rule or forwarding address surprises you, secure the account before anything else.
• If your mail goes through a filtering service, check its message history and quarantine too. iBlockSpam keeps 30 days of message history per domain and sends each user a quarantine digest, so a held message is easy to find and release. See how it works.

Browse more guides on running email day to day.