The problem is with the person using Reader!
Have you checked the restrictions about mailing a PDF using Reader?
Some of the issues are:
The form has been changed, so it needs to be saved.
Can Reader save a completed form?
Reader needs to access the email client.
Acrobat only can use email clients that use the Windows MAPI.
Email is very insecure and if any very personal data like credit card number, debit, card number, checking account information, etc is being gathered, then email should not be used. You need to use a secured server to receive the data and process the form and send out a confirmation email that does not include the personal sensitive data.
Have you applied 'Extended Reader Rights' to the PDF you are distributing?
Using a submit to a web server, does not require these extended rights.
All permissions are granted. No security enabled.
No credit/debit information is not needed on this form. It's a "simple" registration form with name, address, phone number, etc so, it does not have to be secure.
I can save the form to a desktop and send that way but, that is not going to make my client happy to have a "work around" like that.
So you have applied the special "Extended Reader Rights"?
This is an advanced action beyond the simple security of the property of the PDF. The Security tab will have a special note about the form having special extended riights.
You may want to follow up as to what the user with the problem has for a computer, an OS, email client, and version of Reader. Note if the person with the problem has a MacIntosh, there are many know problems with MacIntosh's Preview application that can read PDFs but does not handle forms very successfully.
I have extended Reader rights. Still doesn't work.
As for following up with users, there would be many, many users that I don't have direct contact with.
Also, if a person wants to sign up for this event and the form doesn't work, they will, most likely, just move on and not register online.
Do you have a link to the form that's been Reader-enabled?
That form is not Reader-enabled.
If the form had the Extended Reader Rights, then there would be a statement to that fact at the bottom of the "Properties - Security" window as highlighted below:
You may also want to test the emailing method you have selected on various platforms with various email systems. People using web based services like gmail, yahoo mail, netzero, etc may have problems with this method.