Has it worked before? Have you tried restarting your droplet? If you installed a firewall, did you open the necessary ports? Have you created an SPF record?

Also, I don't think Google allows unsecure connections (i.e. on Port 25). I think it requires TLS on the default port: 465. See How To Use Google's SMTP Server.

triavi.com. 1800 IN TXT "v=spf1 ip4:37.139.30.113 -all"
telnet aspmx.l.google.com 25 works (it uses ipv4)
telnet to my host works as well.
I'm not trying to use it's smtp,-it's an email forward (via /etc/postfix/virtual)

OK, this one seems resolved - the issue was in IPv6,
Just set inet_protocols=ipv4 in /etc/postfx/main.cf, restart postfix.

Now emails are forwarded:
postfix/smtp[3819]: EFC4D1C11D5: to=, orig_to=, relay=aspmx.l.google.com[173.194.69.27]:25, delay=6.3, delays=0.3/0/5.2/0.73, dsn=2.0.
0, status=sent (250 2.0.0 OK 1384239619 cl1si1153461bkc.228 - gsmtp)

status sent, but not appear come to gmail, but this is another story :)

RE: your SPF record

Change the -all to ~all. You may also want to run through the SPF Wizard.