I’ll introduce how to use Onamae Email with IMAP.
I researched how to use IMAP to migrate emails from Onamae Email using Google Workspace Data Migration Service.
データ移行サービスを使用してメールを移行する - Google Workspace 管理者 ヘルプ
According to the help article below, it seems you can use the POP server even when connecting via IMAP.
【共用サーバーSD】【お名前メール】IMAPでメール利用はできますか?|ヘルプサポート | ドメイン取るならお名前.com
Server Host NameThe POP server that can be confirmed in [Server Information] in the control panel
For how to check the POP server, please refer to the following: ▼ Shared Server SD Utilization Guide Server Information Overview ▼ Onamae Email Utilization Guide Server Information Overview
That’s all from the Gemba about using IMAP to migrate emails from Onamae Email using Google Workspace Data Migration Service.