The recent changes to MailerModel to support port and authentication aren't implemented in quite the same way as the MailReaderSampler (however, they are more similar to SendMailCommand).
In MailReaderSampler, the port is not saved in the properties, but is provided in the Store#connect() method call. This is closer to the example in the JavaMail API documentation. Perhaps we should consider using the same method; it's less reliant on poorly documented property names (AFAICT, mail.smtp.port is only documented in the Javadoc for com.sun.mail.smtp, which is a vendor-specific class). Note that the properties should always be set as Strings, even if they are interpreted as int, so the port needs to be set as a String. I think it's currently set as an Integer (boxed from int). In the longer term, maybe we should consider sharing some code between SmtpSampler and MailerModel; both create and send messages over SMTP.
