message content rejected due to suspected spam

Hi. An email recently sent by our club president to the "officers..." email address we use for club exec business was rejected as suspected spam. This was to a longstanding member with the same email address i.e., no change to her email details on our club website. She is a member of multiple clubs & therefore receives lots of emails. She now has a dedicated email address for Toastmasters business which I have made her primary email address on our website (moved the problem email to the 'secondary' field.
I've attached a copy of the 'message not delivered' email our president received for your reference.
I would be grateful if you would advise of any additional steps I can take to ensure this does not recur or any other suggestions you may have.
Many thanks,
Kristen

You need to talk to bigpond.com their email service they are the ones blocking the email. Bigpond is a real issue with the way they handle email.

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The following addresses had permanent fatal errors

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<sharpscastle@bigpond.com>
(reason: 558 5.7.1 608230B816C88288 Message content rejected due to suspected spam. IB703)

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Transcript of session follows

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... while talking to extmail.bigpond.com.:
>>> DATA
<<< 558 5.7.1 608230B816C88288 Message content rejected due to suspected spam. IB703
554 5.0.0 Service unavailable