Temp/Logs directories "not writeable for the webserver"

[KiwiBloke]

Hi, wondering if someone can help me. I've installed RoundCube 0.2.1 on two servers I have access to - each one is a hosted website from a different ISP. I uploaded the RoundCube files via FTP to the site and went to the /installer URL and stepped through the installer. With both installations, the folder permissions for all of the subfolders were set to 755.

When I got to the 3rd step of the installer, on the first website ("Site A") it gave me a clean bill of health - I got a nice, green "OK" on every check there, including "Check if directories are writable".

However on the other website ("Site B"), I got a green "OK" for everything except for "Check if directories are writable" - on that one it said:
temp/:  NOT OK (not writeable for the webserver)
logs/:  NOT OK (not writeable for the webserver)

I double-checked the folder permissions on the temp and logs subfolders, and they were set to 755, same as the other server.

So I tried changint the folder permissions to 775 instead - no joy. Then I changed them to 777, and finally I got the green "OK" for them both. But I think it's unwise to have those two folders set to 777, right?

So I'm wondering why it works with 755 on the one site, and not on the other one. I'm afraid I don't know a whole lot about website folder permissions other than how to change them using my Windows FTP client.

Incidentally, if I click on "properties" for either subfolder using my FTP client, it shows "User: ftp" and "Group: ftp" - for both websites - ie. "ftp" is the name of the user and the group which those two subfolders belong to. Dunno if that's relevant.

Also, if I leave the permissions on Site B set to 755, and log into RoundCube, it will let me log in and send/receive emails, but no logfiles get created in the /logs folder. But when I change the permissions to 777 then the logfiles do get created there.

Is there perhaps something I can check or change using SSH or something like that? I think I have SSH access to the server (both are Linux-based servers running Apache with PHP etc).

Any ideas?

Cheers,
Jeremy