We are using the Time Tracking capabilities in JIRA. We have set the hours per day to 6 and days per week to 5. We use 6 hours per day because we know we have overhead activities that limit a developer's time on JIRA issues to around 6 hours per day. This is all working fine except for some details that come out in the email notifications. In the summary column on the left side of the email message, the 'Original Esitmae' and 'Remaining Estimate' are using an 8 hour day instead of a 6 hour day. So, if I put 18h in as the estimate, the Issue itself correctly converts this to 3 days, but the email states it is 2 days 2 hours.

Attached [to the original support issue] is a screen shot of the email notification I received after modifying the original estimate of an issue from 16h to 18h. You'll see that the body of the email has all the correct values in it, but the summary column on the left is incorrectly converted.

Reported as support request https://support.atlassian.com/browse/JSP-6570 See there for screenshot.