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email error troubleshooting


How to fix “550-previous (cached) callout verification failure” email error

Spammers have made life difficult for us all.

These days even legitimate mails get snagged in the vast array of anti-spam defenses deployed by companies.

One such commonly misclassified anti-spam bounce is:

user2@recipient.com
SMTP error from remote mail server after RCPT TO:<user2@recipient.com>:
host mx.sender.com [x.x.x.x]: 550-Verification failed for <user1@sender.com>
550-Previous (cached) callout verification failure
550 Sender verify failed

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