How to change the welcome email in osCommerce
The content of the welcome email message sent to new customers in osCommerce can be changed by editing the following file(s):
catalog/includes/languages/XXXXX/create_account.php
Where XXXXX is the subdirectory for the language you wish to change the welcome email for. For example “english”. There are a number of texts that appear in the welcome email. They are beginning with:
define('EMAIL_
Make sure you make the same changes for all the languages your site supports.