A: Hello Vito, We're sorry to hear you've gotten flagged with your sending. Email Sequences sends from your email servers, not our own so the IP address is from your mail server.

If you're currently on on a trial 365/Exchange subscription, you would need to reach out to your provider's support team: https://support.microsoft.com/en-us/topic/ndr-error-codes-550-5-7-703-550-5-7-705-550-5-7-708-and-550-5-7-750-f5675801-1846-4d1c-9599-5b4e26a9175d#:~:text=the%20block%20removed.-,550%205.7.708,-The%20complete%20NDR

If that's not the case, it's possible the sending email address you're using might be on your org's blocked sender list as suggested here: https://answers.microsoft.com/en-us/msoffice/forum/all/550-57708-service-unavailable-access-denied/274f6e9e-9ecf-4122-ac22-adac97e3f337

That said, since we don't know your domain, we can't say for certain, but it is possible that if you tried sending an unauthenticated email (no/misconfigured DMARC/DKIM/SPF) it could have gotten your sending email address blocked.

For further support, email us at me@voilanorbert.com. We'll be happy to help.