Zen 1.3.7.1

All latest patches

The user forgot-password tool had been working okay but is now not sending passwords.

I'm not sure when this changed, customer just said that they tried it but did not receive a new password (no email received)

However, shopping cart order emails do go out okay, received, etc.

Any idea why the forgot-password would not send out emails but the shopping cart order emails go out fine?

Many thanks