There are many reasons why problems may occur with receiving emails. The following points will help you pinpoint the cause and solve the problem. Please note: problems with email reception may originate with the sender as well.


You have problems sending emails, the article Sending Emails Is Not Possible aims to help you at finding a solution.

Undeliverable Message to Sender

The sender of an email message addressed to you has received a message stating the email is undeliverable.

If IONOS mail servers have a problem delivering an email to their recipient, a bounce message with a status code will be sent to the sender. The article SMTP Error Messages of the IONOS Mail Servers lists the status codes and informs about the reasons for bounce messages such as “Undeliverable”.

Configuration of your Email Program

Faulty or incomplete settings in your email program configuration disable email download.

Check all configuration settings in your email program, especially server address and port. You can find configuration instructions - categorized by email program - in the Help Centre under the collapsible list items in Email > My Emails.

Your Email Program Does Not Support TLS 1.2

Email access either without encryption and through the TLS 1.0 and TLS 1.1 protocols have become deprecated, meaning they do not meet current security standards. Access to our email servers by any of these methods will be disabled in order to protect your email communications. In order for the transmission of emails between your device/email program and our email servers to continue working, they must support the TLS 1.2 protocol or higher and encryption (SSL/TLS) must be activated.

Check the documentation for your device or email program to see if it supports TLS 1.2. If necessary, update the software in question. The latest versions of the most common email programs support the more secure versions of TLS 1.2 and TLS 1.3.

You should also make sure that encryption (SSL/TLS) is enabled on your device or email program. The next section explains the proper settings you should use.

For more information, please read this article describing how to enable SSL encryption in an email program, including a list of more specific articles that describe how to configure SSL encryption in the most common email programs (Outlook, Thunderbird, Apple Mail, etc.).

Mailbox Quota Exceeded

The sender gets the message an email cannot be delivered do to missing storage space (quota).

IONOS mailboxes may have a maximum size in some packages. Check the available storage space and delete emails with large attachments. Please note: Emails in the sent folder use up storage space as well.

Filter Rules

A filter rule will delete or move incoming emails.

Temporarily deactivate all filter rules. If email reception is functioning after this action has been taken, please reactivate each filter rule individually. For further assistance please use the online help or the website of your email client or your webmail interface.

Falsely Classified as Spam

An incoming email was falsely classified as an unwanted spam mail and was moved to your spam folder either by Webmail or by your email program.

Check your spam protection settings and customize them according to your needs. The spam settings of your email program or Webmail provide you with the option to disable spam protection for specific email addresses.

Firewall and Virus Protection

A security program such as a firewall or a virus scanner is blocking incoming connections.

Deactivate your security software for test purposes. If emails are being received, check your security software and adjust the settings. Note: Please be aware, a block by security software is likely to occur in conjunction with an actual threat.

Your problem has not been described

Your problem has not been described and is still in existence.

Check on the IONOS Status Page under the node mail system if an incident has occurred. If there is no disruption of global services and you didn’t find the answer you were looking for, we’d be happy to assist you.

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