If you are having issues with sending email, watch this video to see if your Internet service provider may be blocking your SMTP settings.
One of the most common reasons for users not being able to send email is their Internet service provider blocking the 123-reg SMTP outgoing settings, or the port which is email is being sent through.
We recommend you check with your Internet service provider and check with them if you are required to use their SMTP settings to be able to send emails.
For more information on this common issue and how to fix it, read our support article here: https://www.123-reg.co.uk/support/answers/Video/Email/having-trouble-sending-and-receiving-emails-4110/
Publisher: 123 Reg
You can watch this video also at the source.