In a previous post (Joomla forms (PHPMailer) do not work with mini_sendmail) I have written about the phpmailer (a PHP library to send mails) issue in combination with mini_sendmail. The bug has been fixed in phpmailer version 5.2.2-beta2 by introducing a new setting parameter to disable sendmail options - but still a lot of PHP applications use older phpmailer versions (see Follow-up on the Joomla mailing issue with mini_sendmail for Joomla).
Today I got aware that modified e-commerce shop also has issues with mini_sendmail because an old phpmailer class is used in the shop's backend system. The currently latest version 1.06-r4642 uses the phpmailer class in version 2.0.4 where of course the bugfix doesn't exist.
After a successful installation of modified shop on a chrooted shared hosting, the bug can be reproduced pretty easily by creating a new customer account. Once the form was filled with all required information, the shop should send a mail to the new customer. Instead the following error message appears:
Message was not sent
Mailer Error: Could not instantiate mail function.
Looks similar, doesn't it? It's the same error message also seen in Joomla.
The bug is now reported in the modified shop bug tracker (http://trac.modified-shop.org/ticket/144).
So in case you want to use modified e-commerce shop on a chrooted hosting using mini_sendmail instead of the "normal" sendmail, you will have to wait until this issue is fixed or you can use the following workaround:
In the E-Mail Options (Administration -> Configuration -> E-Mail Options) the e-mail transport method can be changed to smtp like this:
This will connect to the mailserver listening on the local machine on port 25 which works with mini_sendmail, too.