Since users were unaware that not all their e-mail messages were being replicated to Outlook, they often failed to respond in a timely manner to affected messages, according to problem reports posted to the Google Apps discussion .

Once aware of the bug, the affected users typically got into the habit of checking Gmail's Web interface periodically to see if all inbound messages had reached their Outlook application.

Google started rolling out a patch to fix the problem Wednesday afternoon and expects to finish in the coming days, a Google spokeswoman said. "Once the rollout is complete, we will re-download any missing messages to affected users," she said via e-mail. "As we noted in the help center, the bug only affected a small number of messages for a very small number of users."

Since the patch will be applied to Google's Gmail servers, neither Apps administrators nor end-users need to take any action.

Google acknowledged the bug in the Google Apps discussion forum on March 12 and had promised a fix for early last week. In the forum, a Google representative said the bug was introduced via a software upgrade earlier in March, but some Apps administrators posted messages saying they've had the problem for longer.