Email sending errors

Sometimes issues with sending emails may occur, but you only see the error message and it’s not always clear what to do next. Below is a table with common errors and recommendations on how to resolve them.

Error Code	Error	Description
20.8	Blacklisted IP	The IP address is blocked by Mirohost. Please contact hosting technical support for more details about the incident
34.4 35.0	Mailbox email@domain.com disabled	The mailbox is disabled. The user receives a notification with a link. To restore access, follow the link and complete the CAPTCHA
50.1 50.2 50.4	Host IP is listed in RBL; Host IP is listed in multi RBL	Your IP address has a suspicious reputation in one or more public blacklist services. Check the IP reputation using the link in the error message or visit: https://mxtoolbox.com/blacklists.aspx and follow the recommendations to clean up the IP reputation
82.1	Blacklisted file type	Invalid file type; the email attachment has a potentially dangerous extension. Archive the file or temporarily change its extension and try sending the email again. Make sure the attachment size does not exceed 50 MB
85.3	Message rejected: malware found	The email or its attachment contains suspicious links, characters, or images. If there is an attachment, archive it. If the email has no attachment, move the email text into a file, archive it, and attach it to the email. Then try sending again