Check that you have enabled the Email action; it is disabled by default.
If you are using Joomla then ChronoForms will use the Joomla mailer settings by default. This is usually the best method. If you need to use a different mailer you can configure it in the Forms Manager settings - please don't use these settings unless you know that they are necessary for your site.
Make sure that your site can send emails from other components. The two that should work are either the User Registration emails or the 'Email a friend' link that appears on article pages. If you try these and do not receive the email you may need to check that your site is configured to send emails. The settings are in the Site Admin | Global Configuration | Server page. Your web host will have help documents to let you find the correct settings. If you are using a local server on WAMP, LAMP or MAMP these do not always include a mail server and you may need to link to a remote SMTP server like GMail.
Make sure that the domain name of the From Email address matches your site domain. If not your mail server may take that as a sign that your site is being used to 'relay' spam email.
Create a very simple test form in ChronoForms with just a Submit button in the Preview box, a Show HTML action in the On Load event and an Email action in the On Submit event. In the Email action configuration only use the Static tab. Put any helpful strings in the Subject and From Name boxes. In the From Email box put info@site_domain.com - making sure that the address matches the site domain. In the To Email box use an email address that you know to be working and to have limited spam filters. GMail is good - you can check the spam box; corporate accounts and popular accounts like hotmail.com, live.com, aol.com, etc. are not useful for testing as it is likely that 'spam' emails will just be deleted. Save the form and check to see if emails are delivered.
If you see the error message "Could not instantiate mail function" please check this FAQ
We have seen a few cases where IP addresses have been black-listed by some mail services. This seems to happen most often when a site has a variable IP address and one used by a spammer is later allocated to your site. You can check your Mail Server IP address online, for example at dnsbl.info
We have a report that BlueHost, and possibly other hosts, may block emails that include an IP address - you can test this by turning the option off in the Email action settings.
Make sure that the To Email address and the From Email address are different, some mail services will drop emails if they are the same. If they both use the site domain then make sure that you use info@ for one and admin@ for the other . . . or some other prefixes.
Drag a debugger action into the On Submit event and submit the form again. You should now see a 'dummy' email in the debug output. Check that the addresses are correct; look for any error messages. It will normally say 'An Email has been sent SUCCESSFULLY . . . '; unfortunately this isn't a wholly reliable message as the standard ChronoForms Email action doesn't fully reflect the response from the Joomla! mailer. If you think that there is a problem here try the Email [GH] action (for CFv4 only) where this bug has been fixed.
If you see any Joomla! Error messages please search for a FAQ on that Error Message as there are a couple of special situations that may cause problems.
Once you have the simple test email working correctly add extra features like dynamic values and file attachments and test each of them before adding the next one. That way you'll know exactly where the problem is.
In general do not use the Dynamic From Email address option; if the From address of your site does not match the site domain there is a much higher probability that your emails will be treated as spam. Instead use the Dynamic Reply To Email and Name options.
Make sure that you have either static or dynamic options at least for To, Subject, From Name and From Email.