SMTP Server errors
If you can’t use our outgoing mail server, it’s likely that you’re using a Popbox, which must be migrated to a Mailbox. To do this, please follow the instructions outlined in the following article: Migrating your Popbox to a Mailbox
Why can't I use the 123 Reg SMTP server?
If you are getting the error message 550 Relay Denied, it means that the outgoing mail server cannot verify who you are and will not allow you to send mail. To fix this, you should use the SMTP server for the provider you have used. For 123 Reg, this will be smtp.123-reg.co.ukMost Internet Service Providers restrict access to their outgoing mail servers to prevent spam from being sent through their mail servers.