RE: Email Config on GP 2018
Not knowing your environment I won't comment on the 30-40 hours.
With Dynamics GP, there are two options to use for email functionality: Exchange and MAPI
First, if you're using a 64-bit email application, such as Outlook, you must use Exchange. If 32-bit, then you can use either Exchange or MAPI
Exchange will prompt you with an Exchange Log On window where users will enter their Exchange credentials to be authenticated, this doesn't require, nor use Outlook on the same machine. This is true whether using an on-prem Exchange Server or Exchange Online.
MAPI does use a default mail profile setup on the machine that Dynamics GP is installed onto to send email through.
I'd recommend looking online for Dynamics GP email information, as we've published multiple blogs regarding this information as well.
Let us know if you have any questions.
Thanks