You need to check out mail recipient address. You need to check out internet connection, server settings, etc. Bigpond technical professionals are reachable through toll-free helpline number. It is open for 24x7 hours. If you find out difficulties to fix it then you can ask the Bigpond email customer service team.
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If you can receive emails but can not send emails this usually means the authenication required by the outgoing (SMTP) server is not configured. ... 'My outgoing (SMTP) server requires authentication' is not checked. In Outlook it is in advanced settings.
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