Fatal Error when SPF not resolved; Error Log not obvious

[MillerMedia]

Issue brought up by a user with this stack trace in the error log:

[Thu May 02 21:16:02.572984 2019] [php7:error] PHP Fatal error: Uncaught Mandrill_Exception: wpMandrill Error: : in /nas/content/live/angelgift/wp-content/plugins/send-emails-with-mandrill/lib/mandrill.class.php:100\nStack trace:\n#0 /nas/content/live/angelgift/wp-content/plugins/send-emails-with-mandrill/lib/mandrill.class.php(111): Mandrill->request('users/ping')\n#1 /nas/content/live/angelgift/wp-content/plugins/send-emails-with-mandrill/lib/wpMandrill.class.php(640): Mandrill->users_ping()\n#2 [internal function]: wpMandrill::askAPIKey(Array)\n#3 /nas/content/live/angelgift/wp-admin/includes/template.php(1653): call_user_func(Array, Array)\n#4 /nas/content/live/angelgift/wp-admin/includes/template.php(1611): do_settings_fields('wpmandrill', 'wpmandrill-api')\n#5 /nas/content/live/angelgift/wp-content/plugins/send-emails-with-mandrill/lib/wpMandrill.class.php(290): do_settings_sections('wpmandrill')\n#6 [internal function]: wpMandrill::showOptionsPage('')\n#7 /nas/content/live/angelgift/wp-includes/class-wp-hook.php(286): call_user_func_array(Array, Array)\n#8 /nas/content/live in /nas/content/live/angelgift/wp-content/plugins/send-emails-with-mandrill/lib/mandrill.class.php on line 100, referer: https://www.theangelgift.com/wp-admin/options-general.php?page=cloudflare

Appears to potentially be an issue with the 'users/ping' endpoint. This could be similar to removing support for another unsupported endpoint here in this pull request: #39

Mandrill's API documentation is not up to date.

[MillerMedia]

@andrewhilson This may be an issue you could handle since you had tested and confirmed some other endpoints were no longer being supported as well. Thoughts?

[MillerMedia]

It appears that this was a result of the SPF records not having resolved in Mandrill at the time of the error. This is an easy fix except it wasn't clear in the error logs that this was the case so possibly there is a way to make it more verbose. I am going to change the title of this issue to be more descriptive.