A new version, 3.0.12, fixes an issue with sending the mail queue in the browser. If you are affected by this problem, you will want to upgrade. If you had not noticed the problem, there is no need to upgrade.
Many thanks to our community members for reporting this in the forums, duncanc for alerting the dev-team about it, kenh and rich0452 for helping to find the issue and checking that it has been resolved, and DragonRider for updating the community about the progress on this issue.
As usual, downloads are available via Sourceforge.