Function deltachat::imap::get_uid_next

async fn get_uid_next(context: &Context, folder: &str) -> Result<u32>

uid_next is the next unique identifier value from the last time we fetched a folder See https://tools.ietf.org/html/rfc3501#section-2.3.1.1 This method returns the uid_next from the last time we fetched messages. We can compare this to the current uid_next to find out whether there are new messages and fetch from this value on to get all new messages.