Function deltachat::imap::set_uid_next

pub(crate) async fn set_uid_next(
    context: &Context,
    folder: &str,
    uid_next: u32
) -> Result<()>

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 function is used to update our uid_next after fetching messages.