Email from the user is rejected. if this is a trusted email account, you can add that email from checking from sender verification. Follow the following steps,
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Login to WHM
1. Click Service Configuration -> Exim Configuration Editor
2. Under Access Lists, find “Whitelist: Bypass all SMTP time recipient/sender/spam/relay checks” and click [EDIT]
3. Add the IP address for the sending server for which you wish to skip sender verification (as the note at the bottom explains, hosts cannot be used in this list)
4. Click Save
5. Click Save again near the bottom of the Exim Configuration Editor page
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Done
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Login to WHM
1. Click Service Configuration -> Exim Configuration Editor
2. Under Access Lists, find “Whitelist: Bypass all SMTP time recipient/sender/spam/relay checks” and click [EDIT]
3. Add the IP address for the sending server for which you wish to skip sender verification (as the note at the bottom explains, hosts cannot be used in this list)
4. Click Save
5. Click Save again near the bottom of the Exim Configuration Editor page
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Done