I guess that the best way to create a subscription form. However, the error messages page cannot be customized. I would love to have the option to change the invalid email message on the CM site.
Also, it would be great to set the mandatory fields on the form and the CM handler would recognize that and display and appropriate message.
I know that this falls well inside the API development but for someone that does not want to touch the API such an option would be great.
The best way to do this (without using the API) is just to do some validating on your own site before submitting the forms.
See our post at http://www.campaignmonitor.com/blog/post/1766/making-certain-fields-required/ for a way to get started.
Thank you Mathew. That is really helpful and dead easy!
I'm glad we could help!