Is SMTPQ an SMTP Server?

The SMTPQ service is not an SMTP server. It’s a service that watches a directory
for special .eml files. When a .eml file appears, it reads it, extracts and removes information
from the header and sends the email by connecting to an SMTP server.
The information extracted from the .eml includes the SMTP hostname, login, password, and other
sending-params.

The purpose of the SMTPQ service is to move to move the mail-sending to a process outside the
application. There are several reasons:
1) To send via SMTPQ, the application writes a file and returns immediately. It is not a time-consuming process.
2) If the computer is shutdown or crashes, the SMTPQ will pick up where it left off when the computer is restarted.
3) The SMTPQ will retry sending in cases where temporary problems may prevent the mail sending.