Tommy,

Current version of Xeams will always use STARTTLS if the receiving server supports it and there is no configuration parameter to turn it off. Many servers on the Internet now require STARTTLS and will generate a warning if email was sent without encryption. Gmail is the pioneer in creating this rule.

Although it is true that STARTTLS will add some additional processing, the cost definitely justifies the benefits.

How many emails are you sending out-bound?