Is there any issues with using the 6.5 client to access a R5 server?
Subject: Interoperability with R6 databases and R5 client
Yes, possibly. If you’re talking about mail, some options that the client presents you will crash the Notes client - for example, creating certain mail rules, trying to upgrade the folder design, adding a user to the blacklist, etc.
As long as you don’t do anything that R5 didn’t have, then it can work, but be cautious. Note that I’m referring to using the 6.5 mail template as well. If you keep the R5 template, then there may be less problems.