Why does some email I send get bounced back with the error message 554?
The reason the email was blocked may vary. If a sender encounters this type of bounceback when sending to an account in our systems, the text of the error will generally indicate where the difficulty lies. The two most common 554 errors are listed below:
"554 The message was rejected because it contains prohibited virus or spam content"
There may have been a virus infected file attached to the email. It can also mean that the email triggered our phish filter. You can try to resolve the issue by changing the content of the message and resending it. To avoid triggering the phishing filter, check any links in the email message, as our filters block known phishing links in email messages. Try sending an email that contains no hyperlinks to see if it is rejected. If the email you are sending contains any advertising or embedded images, remove those as well before sending the email.
"554 The message was rejected due to SPF policy"
The server your email was sent from is not in compliance with the Sender Policy Framework (SPF). Your administrator specifies what outgoing mail servers you can use to send messages, and the SPF rejects messages that your administrator does not authorize. Contact your administrator to determine what server you can use, and then update your account with the correct server information.
NOTE: If you are using a third-party email provider or email with your ISP, your administrator would be that provider or ISP.
If you are encountering 554 errors other than those listed above, contact your email provider first to determine if there is anything with that provider that may be influencing the situation.