SMTP Server shows as invalid

This could be a stupid mistake I'm making, but I'm setting up mattermost currently.

Everytime I try to get email working, I keep getting the error:
[2016/07/21 12:12:37 IST] [EROR] /api/v3/admin/test_email:testEmail code=500 rid=qk77pnxid7bqbntk74a1xep17w uid=wp8u63tgf3fbmrtzd6gd6j9eer ip=... SMTP Server is required [details: Invalid SMTPServer parameter]

I'm using the same settings as my jira+confluence instances

I've tried setting the SMTP Server param to an ip and to a hostname but no luck... It always comes up as invalid.

I'm using this version: 3.1.0 3.1.0

Anyone having a similar issue?

Thanks!