It looks your mail realy server is not reachable from Airwave, it is timing out. Is there any firewall between Airwave and mail realy server?
could you send test email to narrow down issue whether it is on Airwave or mail relay server from Airwave.
#echo "Test mail from postfix" | mail -s "Test Postfix"xxx@xxx.com
Please replace xxx@xxx.com. It’s better to run a test with your free email id with gmail, yahoo, etc first. If you can receive test mail sent above then that means postfix is able to send emails.
Make sure, you have configured your mail realy server in AMP Setup > Additional AMP Services section > Use Embedded Mail Server set to YES and provide your mail server details.
If your server reaches to the internet you could try send test mail by setting it to NO and click send test email to confirm whether issue is on mail realy server side.