My Email Isn’t Sending or Receiving Messages: What to Check in Duplika

When a mailbox reaches 100% of its storage, it stops receiving messages and may also stop sending them. Check the mailbox’s usage in cPanel and, if it’s at its limit, increase its storage from Email Accounts.

Also check your plan’s total storage in cPanel under Disk Usage: if your hosting account has run out of space, email will stop coming in and going out, even if each mailbox still has available storage.

If you use POP3 and your email client doesn’t delete messages from the server, Webmail will fill up over time. In that case, we recommend using IMAP, which keeps messages synchronized on the server. You can find the differences and ports for each protocol in POP3, IMAP, and SMTP: Email Protocols and Ports.

If the error mentions Plaintext authentication disallowed on non-secure (SSL/TLS) connections, your client is trying to connect without encryption. For security, we only allow SSL or TLS connections: enable SSL/TLS in your account settings.

Use these settings for your email client: incoming and outgoing server mail.tudominio.com (replace tudominio.com with your actual website domain), your full email address as the username, IMAP on port 993, POP3 on port 995, and SMTP on port 465, all with SSL enabled. If your client can’t connect on port 465, try port 587 with TLS.

If the error is SMTP Error: Could not authenticate, your login details are incorrect: reset the mailbox password in cPanel and set up your client again. If your client repeatedly tries to connect with an incorrect username or password, the connection may be blocked: check your credentials and make sure you can sign in to Webmail with the same account.

If connection errors affect POP, IMAP, and SMTP at the same time, your internet connection’s IP address may be on a blocklist. In that case, ask your internet service provider for a clean IP address.

If you received a delivery failure notice, paste the error line into the HostingFAQ bounce analyzer. It helps you identify the error code and what to check first. Keep the original notice so you can share it with support if needed.

The exact bounce message determines the solution:

• 550 5.7.1 [CS] Message blocked: our anti-spam system detected characteristics of spam; this may be a false positive triggered by words, URLs, or all-caps subject lines in the message. The bounce includes a link to report it, and once reported, your emails should send normally. If the problem keeps happening, forward the bounce to support so we can look into the reason.

• 550 5.7.1 [ESA] Sender blocked: sending from your account has been blocked, often because it was used to send spam. Change the mailbox password from Email Accounts in cPanel, scan your computers for viruses or malware, and let us know so we can restore sending.

• 550 5.7.1 [IRR] Our system has detected unusual activity from your account: many messages were sent to invalid recipients. Check your address list, remove addresses that don’t exist, and try sending again.

• 550 This message was classified as SPAM and may not be delivered: this is usually an anti-spam false positive. Forward the bounce to support so we can review it.

The server rejects your outgoing messages for at least 60 minutes because it recorded too many bounced or deferred emails. There are two most common causes:

• Your domain has SPF enabled without including our email service. Check the settings in SPF and DKIM Configuration.

• Someone gained access to your mailbox and is sending emails pretending to be you. Change the password as soon as possible and use the Track Delivery tool to check who sent those emails.

Emails WordPress sends using PHPmail are often filtered as spam by providers such as Gmail or Outlook. Set the form’s sender address to an existing account on your domain: using a nonexistent address or one from another domain will cause sending to fail. Use that account’s SMTP server to send email: for WordPress, we recommend the FluentSMTP plugin. If only some application emails fail, check the plugin or code that generates them. See Improve email sending from WordPress using SMTP for step-by-step instructions.

If your application sends through an external SMTP server (for example, Amazon SES or another provider), contact us: we need to enable access to external SMTP services on our end.

If your internet service provider filters port 25, use port 9025 to send without encryption or port 465 to send with SSL.

All hosting plans have an hourly email sending limit for the entire account: Inicio 100, Esencial 200, Avanzado 300, Profesional 400, Empresa 500, Roble 600, and 200 per hour for reseller plans. See Email Sending Limits for details.

If you’re sending from an application that opens many connections at the same time, keep the number of connections below 100 every 30 seconds.

If you need to send more email, consider a Cloud Servers plan with a dedicated IP or an email marketing plan.

If no messages are coming in or going out, check the following in order:

• Expired domain: if the sender’s domain has expired, messages will bounce with 550 5.1.2 [SDNF] Sender Domain Not Found. Renew the domain; email may take a few hours to work again after renewal.

• Domain suspended pending contact verification: if the bounce says You have reached a domain that is pending ICANN verification, the domain has been suspended until its contact details are verified. Complete the verification to reactivate the domain.

• If you manage your DNS through Cloudflare, the A record for mail.tudominio.com must point to your server’s IP address, and the MX record must point to mail.tudominio.com; both records must be set to DNS Only.

• Some recipients return 451 4.7.650 The mail server has been temporarily rate limited due to IP reputation. This is a temporary block managed by the destination provider; if you receive this bounce, contact us so we can follow up.

If expected emails arrive in spam, mark them as Not spam in Webmail and add the sender as a trusted sender under Settings > Preferences > Mail Account Configuration > Anti-Spam. We can also add the sender’s domain to the whitelist under Spam Filters in cPanel.

If messages don’t even appear in the spam folder, the filter may be deleting them automatically: in cPanel’s Spam Filters, the Automatically Delete New Spam (Auto-Delete) option deletes email identified as spam. Turn off this option or add the sender to the whitelist under Show Additional Configurations to keep these messages.

We don’t recommend turning off the anti-spam filter as a first step: you’ll let real spam through along with legitimate email.

When the recipient is using Gmail, the bounce says 550-5.7.26 Your email has been blocked because the sender is unauthenticated and asks you to authenticate the domain with SPF or DKIM. In Microsoft and Outlook, the message is 550 5.7.515 Access denied, sending domain doesn't meet the required authentication level. Both indicate that your domain didn’t pass the receiving server’s SPF, DKIM, or DMARC check.

Check and correct these records in cPanel under Email Deliverability: on shared hosting, SPF must include spf.duplika.com. See SPF, DKIM, and DMARC Configuration to Authenticate Your Emails for the complete setup.

Correct SPF, DKIM, and DMARC records prevent these bounces, but they don’t guarantee that a message will reach the inbox: the recipient’s filters may still direct it to spam based on its content.

A misconfigured forwarder can prevent email from being received even when the original mailbox is set up correctly. In cPanel, under Forwarders, check that each forwarder points to an existing address: a forwarder pointing to an address that doesn’t exist can cause messages sent to the original account to bounce.

If you find a forwarder you didn’t set up, delete it and change the mailbox password as soon as possible. Forwarders to external accounts can also contribute to anti-spam systems blocking your outgoing messages.

Errors such as 550 5.1.1 Recipient address rejected are issued by the server receiving the email, not by ours: the address doesn’t exist or that server is blocking the message. Check the bounce to see which server returned the error; if it isn’t from Duplika, the solution depends on the recipient: verify that the address is spelled correctly and, if it is, ask their administrator to check why your messages are being rejected.

A notice such as Warning: message delayed 24 hours isn’t a final bounce: the message is still queued and delivery attempts are continuing. If the destination server doesn’t accept it after the retries, the message will be returned with the reason. Contact us with the full notice so we can follow up.

If your domain uses the MX records for Google Workspace, Microsoft 365, or another provider, that provider handles incoming email, not Duplika’s mail servers. Forms and applications hosted with us may still try to deliver messages locally: in cPanel, Email Routing determines whether the server delivers messages locally or remotely; set it according to where the mailbox is hosted.

If you also manage DNS through Cloudflare or another provider, changes you make in the cPanel zone won’t update public records. See DNS Propagation: How Long It Takes and How to Check a Change to learn how to check for changes.