I will try to answer all the replies.
The mail server i was relaying from is not one that belongs to our company so I can’t set up a specific account on that server. That would be too easy.
These Groov boxes are each on a single LAN with only two or three tcp/ip devices. Each one connects to the Internet through the exact same model Cradlepoint cellular modem using a Verizon cellular account.
Here is the current error I’m getting when I send a test email on the one that doesn’t work:
534-5.7.14 <https://accounts.google.com/signin/continue?sarp=1&scc=1&plt=AKgnsbsX 534-5.7.14 yWMf-N6tR42X4vUzmJuOPdDy2apu1JgBsEZMMMrnT4lv434YRHGial81cmogRkVQyOqjxm 534-5.7.14 r-62SwVTRFBOHqsugqeIEZR6Wwvnp2P_lRMcxw9lPZdR0uZVu_TzrPvlEUY0Be5clnY3XF 534-5.7.14 SQvcE0AkA0SSS8117G869FzteS0_HJCI2AgnzCn58S_656zAD83A1VQMSSkkXSuW9j3Ven 534-5.7.14 6VEIu6sqHTCFfn3qxEldbQCZVo8s8> Please log in via your web browser and 534-5.7.14 then try again. 534-5.7.14 Learn more at 534 5.7.14 https://support.google.com/mail/answer/78754 e71sm3584908pfk.55 - gsmtp
That’s a two-step verification error I’m presuming. However, using another Groov box with the EXACT same email configuration, using the EXACT same Gmail account, I can send a test email just fine.
Here is the config for the one that doesn’t work.
Here is the config for the one that does. The blacked email addresses are the same.