Hi,
I’m using Mailspring on Windows 11 in order to access my iCloud e-mails. New mails are fetched from iCloud and the folder structure is correct as well. However, when I delete a mail on my iPhone, that change is reflected in my iCloud web access immediately. Maispring, on the other hand, doesn’t react. Those mails are still there.
When I view or delete e-mails in mailspring, the changes immediately are shown in the web access and on my iPhone. The only thing that doesn’t work is doing something on my phone/web account and then opening mailspring.
This is a known limitation with iCloud’s IMAP IDLE implementation. Mailspring relies on IMAP IDLE (server push) to be notified of changes made on other devices, but iCloud’s IDLE support is inconsistent — it often doesn’t push deletions or moves made externally. The sync engine does also poll periodically, so changes should eventually appear in Mailspring, but not always in real-time. A workaround is to manually trigger a sync by clicking the refresh icon or switching folders, which forces an immediate IMAP check. Unfortunately there’s no way to work around iCloud’s server-side limitation until Apple improves their IMAP IDLE support.