GMX email could not be sent if the particular recipient is blacklisted. Check whether you can send email to other recipients. If you have blocked any recipients, remove the recipient from the blacklist category. In most cases, you will get a return email message mentioning why the email message is not sent. It is known as a return e-mail (bouncer). If your recipient’s Inbox is full, the person won’t be able to receive any emails. In such cases, the recipient has to free some space to receive your email messages. Consider the procedure that is given below to fix the issue.
If you are still having GMX email could not be sent issue, you can click on the Call button on this page to contact our technical support team. We will sort your issues and fix them at the earliest.