554 5.7.1 Message blocked due to spam content in the message
452 4.2.2 Mailbox full
Cloudn't find any host named ...
Recipient address rejected: user ... does not exist
550 SPF Check Failed
554 5.7.1 Message blocked due to spam content in the message
The content of your e-mail has been blocked by the recipient's spam filter. Depending on the configuration of the filter, the same message may go through to one recipient while being blocked by another. This is particularly common with newsletters.
To ensure that your e-mail is not mistakenly marked as spam, follow these tips:
- Avoid spam trigger words such as "casino", "cash prize" or similar terms
- No titles in ALL CAPS in subject lines or messages
- Avoid excessive punctuation such as many exclamation marks
- Ensure a balanced ratio of text and images
Images should make up a maximum of half the content
- Do not link IP addresses directly in the e-mail
- Do not embed Javascript or forms
- Instead of sending large attachments, use hyperlinks that lead to the download on your website or to platforms such as wetransfer.com
452 4.2.2 Mailbox full
The recipient has no more free storage space in their mailbox. In this case, no further e-mails can be delivered until the mailbox has been emptied or the storage space has been increased.
If you have sent a large attachment, try removing it and sharing it via a service such as WeTransfer or Dropbox instead. Inform the recipient of the error you received, either via an alternative e-mail address or by phone, so that they can empty their mailbox or increase the storage space. As soon as the problem has been resolved, you should be able to receive messages again.
Couldn't find any host named ...
The recipient's domain cannot be found, which is usually due to a typing error in the domain itself, such as a missing character after the @ sign. An incorrect domain ensures that the e-mail cannot be delivered.
To avoid typing errors, copy the e-mail address directly instead of entering it manually. If the error persists, call the recipient to check whether the address is correct.
Recipient address rejected: user ... does not exist
This error indicates that the recipient's e-mail address does not exist. This often happens if the address has been entered manually and a typing error has slipped in. Check the e-mail address carefully - has a letter been swapped or has a space or special character been added by mistake?
It is also possible that the e-mail address was taken from an address book and incorrect characters were added. Therefore, always check the address carefully.
Another possibility is that the e-mail account simply no longer exists. Perhaps the recipient has deleted their account or switched to a new e-mail address. In this case, you should try to contact the recipient by phone or via a different address and ask for a current address.
550 SPF Check Failed
The SPF (Sender Policy Framework) check has failed. SPF is a system that checks whether your e-mails are sent from an authorized mail server to prevent spam and fraud.
The most common reason for this is an incorrectly configured SPF entry in your domain's DNS settings. Use an online tool such as MX-Toolbox to check whether the entry is listed.
What is an SPF entry and how do I create one?
These frequent error messages can block the sending of e-mails, but with the right steps they can be resolved quickly. If you still have questions or need support, we are happy to help you via e-mail or by telephone.
