After I upgraded my Magento to the latest version 2.2.5. The order confirmation emails are not send out anymore with SMTP modules enabled. I have tried different SMTP extensions now, but non of them working. If I disable SMTP modules, then emails are working again.
Is this a known issue with Magento 2.2.5, that it's not compatiable with SMTP? I have tried to google the answer myself, but I could find anything related.
I have tried to send the test emails in SMTP configuration, and I can get the test emails, so I'm sure the SMTP information I entered is correct. But the order emails are not working.