It's a feature that has been requested for many years ... actually, more than a decade.
It's coming. SMTPMailer will have that feature in the next release. It's implemented in developer mode now and being tested. The next release will have:
- IMAP will be added as a transport to send emails
- Will add the sent email message to your INBOX.Sent folder (as an option, and requires authentication)
- Adding to INBOX.Sent will be available regardless which type of mail transport selected
- Preference of Transport, in order: SMTP, Sendmail, IMAP, mail()
- Date format fix to RFC2060 standards.
That is not implemented in PHPMailer Pro yet, but it is planned for the next release.
To answer the question: What's the difference between SMTPMailer and PHPMailer Pro?
Not a whole lot, really not.
PHPMailer Pro is the next generation of PHPMailer. It's a complete re-write of the last version I authored (and hold the copyrights to). PHPMailer Pro can handle everything from one single email to large mailing lists. It supports load balancing with multiple SMTP servers and is very fast. It's a secure application. SMTP functionality is built into the PHPMailer Pro class. Default is SMTP.
SMTPMailer has similar capabilities but with no load balancing. That means it is suitable for single emails to moderate size mailing lists. It may be a bit slower on large mailing lists. SMTP functionality is built into the SMTPMailer class. Default is SMTP.
Unless you are focused on running extremely large mailing lists, use SMTPMailer.