Email is such a pain (I should know, as I'm currently working on a site that's sending 10-20,000 emails per day to 40,000+ users. Spam prevention, SPF records, bounce handling, abuse reports, deliverability, send rates, etc. are all huge hassles that must be dealt with when handling more than a few hundred emails a day.
For testing, I often like throwing in a quick bit of code to send me or someone else a simple email with a few bits of information when something happens on the site, or to test email addresses or formatting. Therefore I like having a quick one-line function call to send an email. In Drupal 6, there was a handy drupal_mail_send() function that would use some default settings and allow you to quickly shoot off a simple email (not translated, not pluggable, etc., but easy to implement).