The simplest way to contact the Editorial Office about a manuscript you are involved with is to do it from the Review Forum. This will ensure that the message is sent directly to the team in charge of the manuscript.
In the Review forum, open the ‘Need Help?’ menu in the upper right of the forum and click on ‘Editorial Office’. This will open a messaging interface.
Please use this link for the full list of Editorial Office's that you can contact: https://www.frontiersin.org/about/contact