Experiencing issues with sending or receiving email? This article covers the most common troubleshooting steps and explains how to determine whether the issue is related to your mailbox, DNS configuration, or spam filtering.
Incoming email Issues
If you are having problems receiving email, check if the email is visible in the email logs (Email logs and delivery) and that you haven't setup a blacklist for that mail address (Email spam filter). If the message is visible in the email logs, verify if the email is visible in the webmail (Log in to webmail (RoundCube)).
When the mail is not visible in the logs or webmail, check whether the sender received a non-delivery report (bounce message) or another error message. These messages often explain why the email was rejected and help finding out the reason why the email was not delivered.
Below are some common error messages and what they mean.
Reject, id=[numbers] - spam
- The message spam level was too high and we automatically reject the message. The sender can best check the content using a mail tester such as https://mail-tester.com, and make the content less spam like, by changing the subject and content of the message.
Service unavailable; Client host [xx.xxx.xxx.xx] blocked using bl.cloud86-dnsbl.io
- Cloud86 can temporarily block emails from IP addresses that recently sent large amounts of spam or showed signs of abuse. Once the issue is resolved and no new spam is detected, the IP address is automatically removed from the blocklist, typically within two days. The sender or their mail provider must investigate and stop the source of the spam before email delivery can resume.
<test@cloud86example.com>: Recipient address rejected: User unknown in virtual mailbox table
- The receiving mail server could not deliver the email because the recipient email address does not exist. The address may be misspelled, the mailbox may have been deleted, or the mailbox has not been created yet.
SPF validation failed. : Reason: default
- The sending server failed the SPF (Sender Policy Framework) check. SPF is a DNS record that lists which mail servers are allowed to send email for a domain. This error usually occurs when the email was sent from a server that is not authorized in the sender's SPF record. The sender or their email provider must update the SPF record or send the email through an authorized mail server before delivery can succeed.
Outgoing Email issues
Contact Form and Automated Emails not working
If emails generated by your website, such as contact form submissions, WooCommerce order notifications, invoices, password reset emails, or other automated emails, are not being delivered, follow the steps below to identify and resolve the issue.
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Check the SMTP settings
- SMTP (Simple Mail Transfer Protocol) is the standard protocol used to send emails reliably through a mail server. Using SMTP helps improve email deliverability and reduces the chance of emails being marked as spam.
- If you are using WordPress, you can configure SMTP with a plugin such as FluentSMTP or WP Mail SMTP. Please refer to the following guide for step-by-step instructions: WordPress: Setup SMTP (FluentSMTP or WP Mail SMTP).
- Most SMTP plugins also include a logging feature (FluentSMTP, WP Mail SMTP), which can provide more information about why the message was not sent successfully.
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Verify the DKIM settings
- If emails do not arrive in Gmail or Outlook, DKIM may not be configured correctly. To configure DKIM, see Setup DKIM.
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Check the domain's email settings
- Are you receiving other emails? If not, it is possible that the domain has not yet been added to the DNS zone (Add Domain to DNS Zone). Another common cause is that your website is now hosted externally and the email settings have not yet been updated to use the correct mail server (Use Cloud86 mail server at external website).
If you have verified all of the above, check the Plesk mail logs (Email Logs in Plesk), to determine whether the message was sent from our servers. If the issue persists, please contact our support team and for the best support include the information listed in How to Contact Support.
Outgoing Emails not working
If the issue is not limited to website-generated emails (see Contact Form and Automated Emails not working) and also affects regular outgoing emails, use the troubleshooting steps below.
Verify SPF, DKIM, and DMARC in your DNS settings. DNS is the system that links your domain name to services such as email. You can find the required settings in Email security and spoofing (SPF/DKIM/DMARC). These records help other mail servers verify that emails are legitimate. If you have recently moved the website then you have to update the email settings using the guide Use Cloud86 mail server at external website.
Your domain's reputation also affects whether emails reach the inbox. New domains often have little or no reputation, which can make email providers more careful with incoming emails. Similarly the content of your email matters as well. Avoid spam-like language, misleading subject lines, too many links, large numbers of attachments, and excessive use of capital letters. Clear and useful content helps build trust.
When your emails still end up in the spam folder, you can test them with online mail testers, such as https://mail-tester.com. This tool checks your SPF, DKIM, and DMARC records, reviews your email content, and checks other factors that affect email delivery. The results show where you can make improvements. For the best result use a natural email, that you tried to send, emails with subject such as Test are more likely to be flagged as spam.
If you send large volumes of email, such as newsletters, marketing campaigns, or promotional emails, consider using a dedicated email delivery service such as MailChimp or Brevo. These services are designed for bulk email and often have a stronger sending reputation, dedicated delivery infrastructure, and tools to help you follow email best practices. This can improve the chance of your emails reaching the inbox instead of the spam folder.
Synchronization issues
Verify the Mailbox
Log in to Webmail and check whether the missing messages are visible there. (Log in to webmail (RoundCube)).
When the email is visible in Webmail but not in your email application, the issue is usually related to your mail client configuration or synchronization. In this case, try removing and adding the mailbox again using Linking Mail to an e-mail client in the e-mail manual. Note: Only messages that are currently visible in Webmail will be restored when adding the mail box again. When in doubt, create a backup of your mailbox before removing the mailbox in your email client.
How to Contact Support
You can contact our support using one of the methods at the bottom of this page. To give you the best possible service, we ask that you always try to provide the following information in case of email problems:
- Sender and recipient of the message
- Date and time the message was sent
- Any error messages or non-delivery reports
- Via which email client the message was sent
- For example: website (SMTP), webmail, Outlook, Windows Mail, Apple Mail, etc....
If you need some help, you can always reach our support desk by email support@cloud86.io and on weekdays from 9:00 to 16:00 (CET) you can also reach us by phone and via the chat in My Cloud86.