Check the following:
1. Make sure that you have set the details correctly in the eCommerce Express Payment settings.
2. Make sure that you have disabled or uninstalled Email Obfuscator Tool in Concrete5. There are a couple of ways to achieve this:
Automatic Email Obfuscator via config
Automatic Email Obfuscator Add-on
For the config make sure it's disabled for the Add-ons make sure it's uninstalled.