Hi @motoyen,
I’m sorry to hear you’re running into issues. It’s possible that you’re running into a configuration issue on your site’s server, which could prevent SMTP from working. The good news, though, is that we can typically track down the source of the issue/help get you back on track.
I haven’t turned up any posts from you in our support forum, but please know we’d be happy to help! You can click here to check out our forum here on .org, where we provide limited complimentary support to all of our free version users.
I hope that you’ll pass along some details so we can try to help get this sorted!