Incorrect authentication data

SPF Some users reported that creating an SPF record solved the issue.https://wordpress.org/support/topic/incorrect-authentication-data-port-587-smtp-starttls-siteground/ Cpanel Possible solutions: Login to CPanel > Tweak Settings > All> “Restrict outgoing SMTP to root, Exim, and mailman (FKA SMTP Tweak) and switch it from “On” to “Off”. The problem may be the cPHulk (login blocking software). So adding the external IP …

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