Short answer. When email is not arriving, start with the two checks that resolve most cases: the Spam folder on the recipient side and the bounce report on the sender side. Then work down the list: the sender domain's SPF, DKIM, and DMARC, the recipient's MX records, blacklists, and mailbox quota. Below is a step-by-step checklist for both scenarios.
Why email does not arrive: the main causes
Almost every "my email is not arriving" case comes down to one of eight causes: the message landed in Spam or a tab you never open; the sender's domain is missing SPF, DKIM, or DMARC; the recipient domain's MX records are broken; the sender's IP or domain is blacklisted; the recipient's mailbox is over quota; there is a typo in the address; the receiving server uses greylisting; or a filter or forwarding rule intercepted the message. Each cause can be tested in minutes, and almost every one has a definitive check. Let's split the problem into two scenarios — you are the sender, or you are the one waiting.
Scenario 1. You send an email and it never reaches the recipient
If your email is not reaching a specific recipient or an entire domain, go through the steps top to bottom — they are ordered by how often each cause shows up in practice.
Step 1. Ask the recipient to check the Spam folder
The most common outcome: the message was delivered and is sitting in Spam. Ask the recipient to search for your address across all folders and click "Not spam" — that trains the filter. If your email consistently lands in Spam for many recipients, the problem is your domain's reputation and authentication — see the guide on why emails go to spam and how to fix it.
Step 2. Check your domain's SPF, DKIM, and DMARC
Without proper authentication, modern providers — Gmail, Outlook, iCloud — either send your messages to Spam or reject them at the door; Gmail and Yahoo now require SPF or DKIM for all senders. Check all three records at once with our email domain checker: it shows which records exist, which are missing, and where the syntax is broken. Manually:
dig TXT example.com +short "v=spf1 include:_spf.example.net ~all" dig _dmarc.example.com TXT +short "v=DMARC1; p=quarantine; rua=mailto:dmarc@example.com"
Step 3. Check the recipient domain's MX records
If the recipient domain has no MX records, or they point to a server that does not exist, there is nowhere to deliver the message — it will bounce after days of retries. A quick test:
dig MX example.com +short 10 mx1.example.net. 20 mx2.example.net.
An empty answer means the domain cannot receive mail at all — send the recipient our guide to checking MX records. To review every DNS record of a domain in one place, use the DNS lookup tool.
Step 4. Check whether your IP or domain is blacklisted
If your messages fail to arrive at several unrelated domains at once, a DNSBL listing is the likely cause. Check your mail server's IP and your domain against the major blacklists; if you find a listing, follow the guide to getting removed from email blacklists.
Step 5. Read the bounce report: codes 550, 552, 554
When a message is rejected, the sender receives a non-delivery report (NDR). The SMTP code states the reason: 550 means the address does not exist or delivery is not allowed, 552 means the mailbox is full, 554 means refusal by policy or reputation. The full breakdown is in the guide to why emails bounce; if you send at volume, automate returns processing as described in the article on bounce handling.
Step 6. A special case: transactional email
Sign-up confirmations, password resets, and receipts need a separate sending stream, separate reputation, and separate monitoring. If it is specifically your website's service messages that keep disappearing, read the deep dive on transactional email deliverability.
Half of all "email not arriving" cases are solved by checking the Spam folder and the bounce report — start there before you touch DNS records or open a ticket with your host.
Scenario 2. You are expecting an email that never shows up
If emails are not arriving in your inbox, most of the checks below take five minutes and require no server access at all.
Spam folder and inbox tabs
Check more than just Spam. In Gmail, messages slide into the Promotions and Updates tabs; in Outlook, the Focused inbox quietly moves mail to the Other tab. Searching for the sender's address across all folders finds the "lost" message more often than any other single check.
Filters and auto-forwarding
A filter created a year ago can silently delete messages, mark them as read, or forward them to an old address. Review the filter list and any active forwarding — especially if the mailbox is used from several devices.
A full mailbox
When your quota is exhausted, the server answers the sender with code 552 and the message bounces. Delete old messages with large attachments, empty the trash, or upgrade the storage plan.
A typo in the address
Ask the sender to show you the exact address the message went to. One wrong character and the email either reached a stranger or bounced with code 550.
The sender's domain is blocked
Your personal block list or a server-side filter may have blocked the sender's entire domain. Check the blocked-senders list in your settings, and on a corporate account ask the administrator about the gateway.
Greylisting delays
Greylisting temporarily rejects the first message from an unknown sender and accepts the retry, which normally comes within 5–15 minutes. If mail from new senders is consistently 15–60 minutes late, greylisting is the reason.
Symptom → likely cause → what to do
| Symptom | Likely cause | What to do |
|---|---|---|
| Message shows as sent, recipient never sees it | Landed in Spam or a tab | Search all folders, click "Not spam" |
| Bounce with code 550 | Address does not exist or delivery refused | Verify the address, read the error text |
| Bounce with code 552 | Recipient's mailbox is full | Reach the recipient through another channel |
| Bounce with code 554 | Policy refusal: reputation or spam filter | Check SPF, DKIM, DMARC and blacklists |
| Nothing arrives at any mailbox of one domain | Broken MX records on that domain | Run dig MX, notify the domain administrator |
| Arrives in Gmail but not in Outlook | One provider's requirements are not met | Check DMARC policy and reputation with that provider |
| Messages arrive 15–60 minutes late | Greylisting | Nothing: the delay is normal behavior |
| Only your website's emails disappear | Transactional stream without authentication | Set up SPF and DKIM for the sending service |
The code in a bounce report beats any guesswork: 550, 552, and 554 each point to a specific cause, and the text after the code usually links straight to the provider's own instructions.
How to stop losing email going forward
A one-time fix does not stay fixed on its own. DNS records change when you move hosting, DKIM keys get rotated, and IP addresses land on blacklists without warning. Make it a habit to run your domain through the email domain checker after any DNS change and at least once a month. If email is critical for your business, put the domain and its DNS records under continuous monitoring — the system will notice a vanished MX record or a broken SPF before your messages start disappearing. Plans are listed on the pricing page.
Frequently asked questions
Why did my email arrive in Gmail but not in Outlook?
Every provider runs its own filters and its own reputation database. Gmail may accept a message with a soft SPF result, while Outlook rejects the same message because of a missing DKIM signature or a poor IP reputation in Microsoft's data. The bounce report names the code and the reason from the server that refused the message.
How long can an email take to arrive?
Normally seconds to a few minutes. With greylisting, 15–60 minutes. If the receiving server is down, the sender keeps retrying for up to 4–5 days, then returns the message with an error. An email cannot be "in transit" longer than that — it is either delivered or bounced.
What does error 550 mean?
A permanent refusal: the address does not exist, the mailbox is disabled, or the server refused delivery by policy. Verify the address character by character, then read the text after the code — it usually names the exact reason and links to the provider's help page.
What should I do when the sender insists the email was sent?
Work from both ends. The sender checks the bounce report and the Sent folder; the recipient checks Spam, tabs, filters, and quota. If there is no bounce and nothing in Spam, ask the sender to try a different address of yours — that shows which side owns the problem.
Can an email disappear without a trace?
Almost never. There is nearly always a trace: a bounce on the sender's side, a line in the server logs, or a message in quarantine. An email that "vanished" is most often in Spam, deleted by a filter, or sent to a mistyped address.
Final checklist
- Search for the sender's address across all folders, including Spam and inbox tabs.
- Verify the recipient's address character by character.
- Read the bounce report: codes 550, 552, 554 and the error text.
- Check the sender domain's SPF, DKIM, and DMARC with the email domain checker.
- Check the recipient domain's MX records with dig MX.
- Check the sending IP and domain against blacklists.
- Review filters, auto-forwarding, and mailbox quota on the recipient side.
- Account for greylisting: wait 15–60 minutes before resending.
- For websites, test the transactional email stream separately.
- Set up regular domain checks and DNS monitoring.