Hi,
Yes, pneumonia is better.
The POP3 issue is not about my app, it's how their server works.
For example, for a while I was dual-booting between Windows and Linux, with a separate copy of Thunderbird in each. If I received messages in Thunderbird/Windows, I'd not receive them again in Thunderbird/Linux, and vice versa.
Gmail provides a so-called "recent" mode for POP3, where it always makes available messages from the last 30 days, it's described at the links above.
As for IMAP, deleting messages from @gmail accounts is certainly possible. I do it every day, sometimes several times before my morning coffee
The right way to delete messages for @gmail, using IMAP, is to "move to deleted", where the deleted folder has to sync with "[Gmail]/Trash" (this is configured automatically in my app) And "Move to deleted" is the default delete mode for every new account....
Can you describe what issue(s) you're seeing when deleting from @gmail using IMAP?