How to check if the SMTP server is working?

Question

Java

I wrote my SMTP server in JAVA. How can I check if it works now?
For ThunderBird, the setup is as follows:
How can I check the performance of my server assigned to port 997 on the local machine?

Answer 1

1. send an email and check whether it was received or not.
2. receive a letter.
3. check the integrity of the data in the results of the execution of points 1 and 2.