Emails not sending

I have set up emails through sparkpost. I tested the connection, sent a test email and received it.

I have a form with an action to send me the results via email. Never received them.

I have set up emails through sparkpost. I tested the connection, sent a test email and received it.
I have a form with an action to send me the results via email. Never received them.

I have this same problem.

I tried do use Cronfig and do not appear any wrong message but still, my campaigns do not work.

I tried to use an external service for cronjob (cron-job.org) and I used this script: https://www.mautic.org/community/index.php/5092-mautic-2-0-up-cronjob-update-2-5-x/0#p13767
But all the commands failed. The messages are:

"Status: 302 Moved Temporarily

Response headers
Date: Fri, 10 Mar 2017 13:15:27 GMT
Server: Apache
Location: /404.html
Content-Length: 0
Content-Type: text/html"

My mautic is 2.7 and I have the last update for php. My server is shared (hostgator).
Sometimes I receive the test e-mails, sometimes don’t.

Could somebody give me an idea? I searched for the mistake at the forum but I do not found the answer.