When email doesn't work, it matters which side the problem is on: you can't send (the message stays in the Outbox or the app shows an error), the message bounces back with a delivery failure report, or you don't receive anything. This guide helps you find out which case it is and what to check. If your messages go out but land in the recipients' Spam folder, see Why my emails go to spam: SPF, DKIM, DMARC.
What you'll achieve
- find out whether the problem is with the app, the mailbox, the domain or the recipient;
- read a delivery failure report (“Mail Delivery Failed”);
- fix the settings in the app or in Enhance.
Before you start
- Try in Webmail, at https://mail.nbt-host.com (see Webmail: how to read your email in the browser). If it works from Webmail, the problem is with the app settings on your phone or computer, not with the server.
- Log in to Enhance at https://server.nbt-host.com, under “Emails”.
The steps
1. You can't send from your app
- The outgoing server (SMTP) must be the same as the incoming one:
mail.domeniul-tau.roorserver.nbt-host.com. - Port and encryption: 465 with SSL/TLS or, if your network blocks port 465, 587 with STARTTLS. Port 25 is not used for sending from apps.
- Authentication must be turned on for the outgoing server, with the full address as the username and the address's password.
- If you recently changed the address's password, update it in the app too, for both incoming and outgoing.
The steps for each app are in Email on iPhone and iPad, in the Mail app, Email on Android, in the Gmail app, Email in Outlook, on Windows and Mac, Email in Thunderbird, on Windows, Mac and Linux and Email in the Mail app on Mac.
2. You get back “Mail Delivery Failed”
The delivery failure report has a code and an explanation in English. The most common ones:
| The message in the report | What it means | What to do |
|---|---|---|
| 550 User unknown, No such user, Recipient address rejected | the recipient's address doesn't exist | check the address, letter by letter |
| 552 Mailbox full, Quota exceeded | the recipient's mailbox is full | let them know another way; if it's one of your own mailboxes, free up space or increase it |
| 554 Relay access denied, Authentication required | the outgoing server didn't receive the username and password | turn on SMTP authentication |
| 550 … blocked, spam, policy, SPF, DMARC | the recipient's server rejected the message as suspicious | see the guide on SPF, DKIM and DMARC |
| Message size exceeds | the attachment is too large | send the file through a download link |
3. You sent too many
From each address you can send at most 200 emails per hour; separately, messages sent by the website's code (forms, orders) also have a limit of 200 per hour. Above it, messages are delayed or rejected. For newsletters to large lists, use an email marketing service.
4. You don't receive email
- Is the mailbox full? In Enhance, under “Emails”, the “Mailbox usage” column. When the mailbox is full, new messages bounce back to the sender. Increase the space from “Manage” » “Mailbox size” or empty the large folders (see How much space you use and what takes it up).
- Do they land in Spam? Look in the Spam folder, in Webmail. If a legitimate sender ends up there, add them to your trusted senders (see Anti-spam filters and the Spam folder).
- Where does the domain's MX point? In Google Admin Toolbox – Dig, choose MX. If your email is with us,
mail.domeniul-tau.romust appear. If something else appears (Google, Microsoft, your old provider), the messages go there. - Routing in Enhance. On the website page, in the “Domains” tab, open the domain: “Mail routing settings” must be “Local mail” if your email is with us, and “Remote mail” if it is with Google or Microsoft (see DNS zone editor: A, CNAME, MX and TXT).
- Is a forwarder or a rule moving the messages? Check “Manage” » “Forwarders” and the sorting rules in Webmail.
5. The website form doesn't send
- Check the sender address in the form or store settings: it must be an address on your domain, created in Enhance, for example
contact@domeniul-tau.ro, not a Gmail or Yahoo one. - Check the address the form sends to: a typo there is a more common cause than the server.
- If messages still don't arrive, set up the website to send through SMTP, with the address on your domain and its password (on WordPress, with an SMTP plugin). The server settings are the same as in email apps. For an online store, also see WooCommerce store: the plan, installation and settings, under order emails.
If something doesn't work
- You don't understand the delivery failure report. Send it to us in full, as an attachment or forwarded, without changing it.
- Messages to a single company (for example Yahoo or a specific domain) always bounce. Send us the report: we will check whether the server's address is on any blocklist.
- No one receives anything, from anywhere. Send us the domain and the time of the last message received. We will check whether the domain is set up to receive mail on the server.