Hi @advantechmsp ,
Thanks for reporting this. I investigated the sending path and found two issues: a recipient-formatting error that could trigger a PHP TypeError after a failed send, and SMTP error handling that could stop the entire batch after a permanent recipient rejection.
Both are fixed in version 1.2.5, now available on WordPress.org.
Could you update and check whether this resolves the problem you encountered? If it persists, please share your MailPoet version, SMTP plugin/provider, and the relevant error message, with email addresses and other personal details removed. Those details would help confirm whether your case follows the same failure path.
Thanks again for flagging it!