Posting this to document what I found in my environment was a fix for the login error 9505, SOAP configuration issue seen by my users.

Sometime during the past two weeks, my users started getting errors when attempting to login to their GroupWise accounts via WebAccess.
Random users, all post offices, but not all users, including my own account.

error 9505
Your post office is unavailable. The post office agent might not be configured for SOAP. Please contact your system administrator.

I changed nothing in our system leading up to the increase in errors.
1 domain, 4 servers, 4 post offices, 1 webaccess (located on server with post office)

Looked in the knowledge base, in the forums... SSL was the common theme..
post offices and webaccess were NOT using SSL, so that should be the issue...

Noticed I wasn't up to date with the latest patch,
Read the notes, saw SOAP mentioned, figured why not... applied the patch, no change in errors.

Found log files in /var/opt/novell/groupwise/webaccess/logs
starting walking through them.... and noticed these entries:
9:40:37, <SOAP>, -, INFO, USERNAME, SSL Error: Could not authenticate server certificate for user, potential MITM
9:40:37, <SOAP>, -, INFO, USERNAME, Exception invoking negotiateLoginRequest: HTTP transport error: Remote host closed connection during handshake
9:40:37, <SOAP>, -, INFO, USERNAME, Unable to connect to the POA @ https://IP-ADDRESS-OF-POSTOFFICE:7191/soap

SSL, front and center. But we are not using SOAP SSL....

Not sure why, but I had the idea to check the certificates on the four GroupWise servers.
The certificates on all four servers had expired, imanager listed them as invalid.

Figured why not, lets fix this issue.

7+ days so far, and the issue/error has not returned.