SMTP random password structure is too weak.
I like the forced random very long SMTP password, however limiting it to hex values (0-9 and a-f) severely limits it's usefulness when used as an encryption routine because an attacker can limit their search in a brute force method with that knowledge.
For full cryptographic coverage the random passwords should utilize more of the available character set.
James Gibson commented
My smtp password was attacked and stolen last month, causing me to pay for 100k emails that the attacker sent via my domain.