Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I keep getting this error when trying to use stunnel to work between my sbs2003 server and office 365 mail server:

stunnel: bind permission denied (wsaeacces) (10013) to

Does anyone have any ideas as to what may be holding onto 110 or what I can do to release it?

share|improve this question

There are two common causes for this error on Windows:

  1. A program is already listening on the port you are trying to bind.

    You can inspect the output of netstat -ab to determine if a process is already listening on port 110, and which process it is. After killing or reconfiguring that process, try binding the port again.

  2. The firewall is preventing the program from binding to the port.

    In this case, you will need to configure the firewall to permit stunnel.exe to listen on the port.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.