Sometimes an email simply does not arrive. There is no instant bounce, just a delay warning a day later or a failure notice after several days. This case study walks through one common version of that problem, mail to one company that never gets through, and shows how to tell whether the fault is on your side or the recipient's, what evidence to collect, and who can fix it.
If mail to one domain fails with "connection timed out", "no route to host" or "all hosts have been failing", your server could not reach the recipient's mail server, so the fix is almost always on the recipient's side. Check their MX records yourself, collect the full delay or failure notice, and send it to the recipient's IT team. Our cPanel and DirectAdmin mail servers keep retrying a temporarily failing message for up to four days before giving up.
1. The case: mail to one company never arrives
A business sends a quotation from [email protected] to [email protected]. Mail to everyone else is delivered; nobody at that company receives anything. A day later a warning says the message "has not yet been delivered", and days later a final failure notice arrives.
Three facts already narrow it down:
- Mail to other domains works, so the sender's account, password and server are fine.
- There was no instant bounce, so the recipient's server never said "no". Nobody answered at all.
- Every address at the company fails, so the problem is with the company's mail system, not one mailbox.
2. How an email reaches the recipient
- MX lookup.Your mail server asks DNS for the recipient domain's MX (mail exchanger) records, which name the servers that accept its mail.
- Connection.It connects to one of those servers on port 25.
- SMTP conversation.The servers greet each other, your server names the sender and recipient, and the recipient's server accepts or refuses the message.
- Delivery.The recipient's server puts the message into the mailbox, or into spam.
A failure at step 1 or 2 means the conversation never started, so the recipient's side has no record of your message.
3. Reading the notice: where did it fail?
Open the delay warning or failure notice and find the technical lines. The wording tells you the step.
| Wording in the notice | Step that failed | Usually means |
|---|---|---|
| "all relevant MX records point to non-existent hosts" / "host not found" | 1. MX lookup | The recipient's DNS is broken, or the domain is misspelled or expired |
| "Connection timed out" / "No route to host" | 2. Connection | Their mail server is down, or a firewall is dropping connections |
| "Connection refused" | 2. Connection | The server is up but not accepting mail on port 25 |
| "retry time not reached for any host" / "all hosts have been failing for a long time" | 2. Connection, repeated | Every attempt so far has failed; the server is still retrying |
| A code such as 550, 554 or 421 with text | 3. SMTP conversation | The recipient's server answered and refused; see the bounce decoder |
In our case the notice said the connection timed out on every attempt. That points to the recipient's mail server, their firewall, or an email security service in front of it that has stopped answering.
Our cPanel and DirectAdmin mail servers retry a temporarily failing message for up to four days, trying often at first and then less often, before sending the final failure (measured on our servers, 24 September 2026). A delay warning is not a failure: the server is still trying.
4. Check the recipient's MX records yourself
You can confirm a DNS or connection problem in a minute. On any computer:
# list the recipient domain's mail servers
nslookup -type=mx client-company.example
# on Linux or macOS, dig gives a cleaner answer
dig +short MX client-company.exampleWhat the answer tells you:
- No MX records, or "can't find": the domain has no working mail setup. Only its owner can fix that.
- MX records that point to a name which does not resolve: a DNS mistake on their side, often after a move to a new email provider.
- MX records that look fine: their server exists but is not answering. Public MX-check websites can test whether it responds on port 25 from the outside.
Also re-check the spelling of the domain in the address. client-compnay.example produces exactly the same symptoms.
5. Collect the evidence
The recipient's IT team will ask for proof that you really tried. The delay warning or failure notice is that proof: it contains the time of each attempt, the server your mail went to and the error it hit.
Send the complete notice, including the technical part, not a screenshot of the first lines. Add the sender and recipient addresses and the date and time you sent the message. Never include your password. If the recipient is not reachable by email, use their phone or another channel.
On Domain India shared hosting you cannot read the server's own mail log. If you need the log lines for a message, open a ticket with the sender, recipient and time, and support can check what the server recorded. On your own VPS, the log is yours: on Exim it is commonly /var/log/exim_mainlog, and on Postfix /var/log/maillog or /var/log/mail.log.
6. Work with the recipient's IT team
Ask them to check four things:
- Their MX records, especially after any recent change of email provider.
- That their mail server is running and reachable on port 25 from the internet.
- Their firewall, including any rule that blocks unfamiliar sending servers.
- Their email security gateway, if they use one. A gateway that is down, or quietly dropping connections from some senders, produces timeouts rather than clear rejections.
Once they fix it, messages still in your server's retry queue are delivered on the next attempt, as long as the four-day window has not run out. After a final failure, send the message again.
7. Other delivery failures and where to read about them
When the recipient's server answers and refuses, the notice carries a code that explains why.
| Problem | Typical sign | Where to go next |
|---|---|---|
| Address does not exist | 550 5.1.1 | Check the spelling; ask for the current address |
| Mailbox full | 552 5.2.2 or 452 4.2.2 | Only the recipient can free space |
| Greylisting | 451 4.7.1, delivered later | Nothing to do; the server retries |
| Authentication failure | 550 5.7.26, 5.7.23 or 5.7.515 | Fix SPF, DKIM and DMARC for your domain |
| Blocklisted sending IP | 554 with a blocklist name | See the blocklist guide below |
| Rate limited | 421 4.7.0 or 4.7.28 | Send in smaller batches |
The full code-by-code decoder is in understanding email bouncebacks. For authentication records, see the SPF, DKIM and DMARC guide; for blocklists, what to do if your email is blacklisted. If you cannot send any mail at all, start with I can receive mail but cannot send it.
8. Where Domain India fits
Email comes with every Domain India shared hosting plan. Outgoing mail is limited per account: 200 messages per hour on cPanel and 1,000 per day on DirectAdmin, so a mailing list does not belong in a hosting mailbox. See do you limit the amount of mail I can send.
If you want email that is separate from your website, Business Email is priced per mailbox, signs every message with DKIM, and gives you the SPF and DMARC records for your domain.
- Priced per mailbox - start with one
- Email at your own domain ([email protected])
- Add and remove mailboxes yourself
- Webmail with calendar, contacts and tasks
The card shows the Domain India list price on 19 September 2026, excluding 18% GST.
Why does email to one company fail when all my other mail works?
If mail to everyone else is delivered, your account and server are working. A failure limited to one domain is almost always on that domain's side: broken MX records, a mail server that is down, or a firewall or security gateway that is not accepting connections.
What does "connection timed out" mean in a delivery failure?
Your mail server tried to connect to the recipient's mail server and got no answer. The message never reached them, so they have no record of it. Ask the recipient's IT team to check their mail server, firewall and MX records.
How long does the server keep trying before it gives up?
Our cPanel and DirectAdmin mail servers retry a temporarily failing message for up to four days, frequently at first and less often later, and then send you a final failure notice.
Is a delay warning the same as a bounce?
No. A delay warning means the server has not managed to deliver the message yet and is still retrying. A bounce or final failure notice means it has given up, and you need to send the message again once the cause is fixed.
How do I check a domain's MX records?
Run nslookup -type=mx followed by the domain in a command prompt or terminal, or use dig +short MX with the domain on Linux or macOS. Public MX lookup websites give the same answer and can also test whether the mail server responds.
Can Domain India fix the recipient's mail server?
No. Only the recipient's IT team or email provider can fix their DNS, server or firewall. We can confirm what our server recorded when it tried to deliver your message if you open a ticket with the sender, recipient and time.
Ready to track it down? Check the recipient's MX records, collect the full notice, and compare the code with the bounce decoder. If you need the server's log lines for a message, open a support ticket with the sender, recipient and time sent.
Mailboxes on your own domain, priced per mailbox, with DKIM signing on every message and SPF and DMARC records provided.
See Business Email