There is no one IP address for smtp.gmail.com. You cannot use an IP according to Google Support docs. Nonetheless, I tried. I pinged it, got the IP (173.194.68.108) pasted it in and hit "Test". Unlike smtp.gmail.com, which the printer is quick to say it cannot find, I get a "No data received" Chrome error message when testing 173.194.68.108.
You say TCP/IP... under Configure Device, in Initial Setup --> Networking and I/O --> Embedded Jetdirect --> TCP/IP, I see the following settings:
ENABLE: ON
HOST NAME: NPI3D488C
PROXY SERVER: ___________
PROXY PORT (1 - 65535): 80
IDLE TIMEOUT (0 - 3600): 270
I don't know what any of those settings mean.
Under the IPV4 subcategory I see the following:
CONFIG METHOD: DHCP
DEFAULT IP: Auto IP
DHCP RELEASE: No
DHCP RENEW: No
PRIMARY DNS: <my primary DNS>
SECONDARY DNS: <my secondary DNS>
I see nothing wrong here.
I have to ask again, because I find this hard to believe: Gmail is not some little-used service. Everybody uses it. Countless millions. And surely, out of those countless millions, someone has bought this printer and said "I'm going to set it up with my Gmail account." I can't possibly be the first person to attempt this. Surely we're overlooking something obvious? Or perhaps it doesn't work at all with Gmail? I could settle for that. Tell me I can't do it, and I'll give up.
Thanks for your help.