Magento 2.3: How to solve the message "Unable to send email"?

Question

I have a problem with Magento 2.3 on the contact page and also on admin with email not been send.

I'm getting this error on the contact page " "Unable to send email".

I have flow up email extension that when i try to go into the email I get this errors:

2 exception(s): Exception #0 (ReflectionException): Class Magento\Email\Model\Source\Variables does not exist Exception #1 (ReflectionException): Class Magento\Email\Model\Source\Variables does not exist

Also on confirmation order that been send out it shows FROM: [email protected] and not FROM: [email protected]

Preconditions:
A Magento 2.3.x instance with at least one product. Reproduced on 2.3.x
Steps to reproduce:

1. I tried update Magento with recently get the recent update and ran the commands to set up upgrade, di:compile, deploy static contents, clear cache, etc to check the issue. It could not solve the error. I checked and found that many of them reported the mail issue with Magento 2.3.0. In there, I can see that some class removed from latest Magento(2.3.0) which was included in the older version. Also, it generate compatibility issue with SMTP module. Please see the URL below for more details. Also, I noticed some compatibility issue mentioned with Magento 2.3.0, Porto theme and MagePlaza extension. I am sure about this and how to solve the error as well. mageplaza/magento-2-smtp#127
2. after reading this: https://stackoverflow.com/questions/52054370/magento-2-email-sender-incorrect I've disabled Amazon plugin and deployed static file. This not affect anything.
3. I've uploaded old jquery version to v3 from v1. Magento2.3.0 core not using latest jquery version.

• PЯINCƎ: What happen when you send test in SMTP MagePlaza extension ? did you well configured it ?

Answer 1

Use this extension for SMTP and check. https://www.mageplaza.com/magento-2-smtp/

The problem might be with smtp module you have used.

Answer 2

If you have third-party mail client installed please check them first. Try to update them to support 2.3 version

You can use default mode of magento or run command compilation and view logs for more information