When troubleshooting a contact form, it is important to know that your hosting account can only send out so much email per hour or day. If you aren't sure what type of hosting you have, you can review: What type of hosting account do I have?.
|Hosting platform||Email limits|
|cPanel||500 per hour|
|Web Hosting||1000 per day|
|Plesk||1000 per day|
|Managed WordPress||1000 per day|