For Gmail, it is new. Until recently, 'download' was only possible through IMAP and POP3 – and could therefore take days or even weeks due to throttling.

And Google's shitty, shitty, broken IMAP implementation.

Most of the dev work on offlineimap is to cope with GMail's weird ideas on what constitutes functional IMAP.

https://github.com/OfflineIMAP/offlineimap

Ah, don't remind me.

In an old job, they used gmail for email, so most of the company used Thunderbird. This worked fine for most of them, but sysadmins got so much email (mostly alerts) that google's crappy IMAP implementation kept breaking so the clients would be constantly syncing, and folder operations such as moving stuff would often take multiple minutes.

My cheap VPS I run my own email on vastly outperforms gmail's IMAP.