With the Gmail Imported Accounts Check extension, you can easily check new mail arrivals for imported accounts on Gmail. By clicking the added button next to the refresh button, a new temporary window will open, allowing you to quickly see if there are any new emails in your imported accounts. Once you have checked the new mail, the temporary window will automatically close, and your mailbox will be refreshed.

Please note that this extension is in its pre-alpha version, so there may be some bugs. If you encounter any issues, you can contact the developer via email or through the provided Google Forms link.

In the future, the developer plans to add an option page where users can customize the texts used to identify HTML elements on Gmail. This will allow users to use the extension in any language, although it currently works in English and Japanese by default.