Add option to filter messages by date

[patrykgruszka]

This PR adds the ability to retrieve only messages within a given date range by passing arguments:

• --start-date START_DATE: Start date for filtering messages (YYYY-MM-DD)
• --end-date END_DATE: End date for filtering messages (YYYY-MM-DD)

[ansemjo]

Thank you very much Patryk!

Could you give an example of a possible use-case to restrict fetching to a specific timeframe? Do you just want to avoid downloading very old messages or do you use these flags to create batches per timeframe (daily, weekly, ...) by specifying start and end times with a script? I'm trying to understand if these options might be better placed in the configuration file.

[patrykgruszka]

In my case it's a mailbox that contains huge amounts of logs. Downloading the whole mailbox would take hours and I only need the most recent. That's the reason for the date filter. Moving the filter to the configuration gives even more flexibility than the arguments. Looks good to me.

[ansemjo]

I've been thinking about this some more and I think that adding end-date to a config file wouldn't really make sense. Either it's a date in the past, then you'll never archive any new mails because normally old mails don't just pop up on your server. Or it's a date in the future, but then you can just stop archiving there.

Either way, I've chosen to just accept your change as-is. Thanks again!