A common reason for this relates to the address not matching your site domain.
To help improve email deliverability and help prevent spam being sent from our network, the 'Sender' address for your message must match the domain name of the website used to send the message.
If this header is set to a domain not assigned to your hosting package, the message will not be sent.
Websites will also be unable to send mail if there is malware found on the site. If malware is found it will need to be removed and another malware scan run before the website will be able to send mail again. More information on malware scanning can be found here.
If you have any further issues please contact our Support Team.
