Problem about using Mandrill Library in Sandbox

Hi , i have some problems about using Mandrill library . i am trying to replace email library with Mandrill library to avoid the limit of 20 mail/per hour,

i try the sample code to send my email,but i encounter the problem of smtp port,can i change the port from 465 to another one(25, 587 or 2525)?

i have check my Mandrill user name and API key, but i still can not solve my problem,is there any step i miss?

thanks for reading my problem.