Tweak - Catch mail send error

[deepench]

All Submissions:

• Have you followed the Everest Forms Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Previously when our Everest Forms Plugin's mail was not being sent or received by end-users, there was no way to know what was actually the issue. This PR introduces a notice displayed to the admin when 5 consecutive email send is failed with a detailed error message or report which will be displayed in our Everest Forms -> Tools -> Logs under evf_mail_errors Log.

How to test the changes in this Pull Request:

1. It is hard to replicate such issues as email will be sent in our local environment.
2. To test this, install any smtp plugin and enable a mailer and configure it to fail. For example, Install WP MAIL SMTP plugin, setup google as mailer and do not configure it fully. A user authentication related error occur while sending a mail from the system.
3. Click on Send Test Email, a detailed error message should be displayed and log should have been added to Everest Forms -> Tools -> Logs section. Verify it.
4. Now try to submit the form, if the mail send failed threshold crosses 5, then a notice will be displayed to the admin in admin area.

Types of changes:

• Bug fix (non-breaking change which fixes an issue)
• Enhancement (modification of the currently available functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully ran tests with your changes locally?
• Have you updated the documentation accordingly?

Change log entry

Tweak - Catch mail send error.

[riteelama]

LGTM 👍

[NirajChaudhary143]

LGTM 👍

[joshianup1]

LGTM 👍

[MILAN88888]

LGTM 👍