If Email is sent from NetSuite in the Sent Email List, but it didn't get delivered to the intended Mailbox and it is not on the undelivered Email list, Where would the mail go?

when you say it's on the sent email list, what's the status? sent email includes all emails, but it could have a status of "not delivered". if it does have a status of "sent", then it's likely some kind of spam filter from the mailbox that didn't receive it. if you haven't set up DKIM then that would be the first place to start to reduce the number of places that identify your mail as spam. if that's already set up correctly, then you'd have to reach out to the person and see about their mail settings/spam filters/etc.

the status is "sent". The DKIM is set up, but this particular Email doesn't get delivered. that Email address receives email but not from NetSuite i guess

gotcha, yeah in that case, assuming it's an internal email address i'd reach out to your own company's tech support (or if it's someone external, ask them to reach out to their tech support) and identify if they can see if that email is getting caught in filters/how they can let it through

I asked my IT guy, he said he doesn't have anything in filter

well often emails from NS come through either as a weird looking address (sent-via@netsuite.com or whatever) or as a spoofed address (it's being sent as your company domain but actually from NS, so to the end email user it looks like it's "spoofing" aka pretending to be from your company email domain, which is the same thing spammers do). so it's not unusual for emails to catch emails in spam filters, but usually setting up DKIM prevents a lot of that since it tells the email servers that it's a legit spoofing.

yeah I might just have to ask him to recreate the email address