Yvette,
The most important part of the message is "Successful Delivery" - the subscriber's mail service accepted the message.? The details are interesting but of no real concern as the message has been delivered and is now in the subscriber's "hands" so to speak.? If you need to follow up with the subscriber/applicant, a direct email is best - either from your email or the Send Message function on the member's page on groups.io.
Toby
Toby Kraft