This usually happens when the mail server is using a protocol or cipher suite that has been known to have security vulnerabilities. To check if this is the case you can try to edit the file "$JRE/lib/security/java.security" (where $JRE is the java install path), and then find and comment out with a '#' the following line:
jdk.tls.disabledAlgorithms=SSLv3, TLSv1, RC4, DES, MD5withRSA, DH keySize < 1024, EC keySize < 224, 3DES_EDE_CBC, anon, NULL
Once you have commented it out, you will need to stop the QIE service from the service manager and then start it back up again.
If this fixes the issue, you may want to contact the system administrator for the mail server and have them update it to use the latest protocols and cipher suites.