Excessive space in `EXISTS` response (with mailboxes > 500 mails)

[palb91]

Davmail does not follow RFC for mailboxes with more than 500 mails, on purpose:

<  * OK [CAPABILITY IMAP4REV1 AUTH=LOGIN IDLE MOVE SPECIAL-USE UIDPLUS] IMAP4rev1 DavMail 6.3.0-3627 server ready
>  0.0 LOGIN e.m@i.l passw0rd
<  0.0 OK Authenticated
>  0.1 CAPABILITY
<  * CAPABILITY IMAP4REV1 AUTH=LOGIN IDLE MOVE SPECIAL-USE UIDPLUS
<  0.1 OK CAPABILITY completed
>  0.2 EXAMINE INBOX
<  *  522 EXISTS
    ^^
   Double space instead of 1 when > 500 mails.

Workaround, in davmail configuration:

davmail.enableKeepAlive=true

References:

• Crash with davmail, due to non standard server's response formatting (space) pimalaya/mirador#10;
• IMAP Select unexpected response mguessan/davmail#343;
• selecting "INBOX" -> response is violating imap protocol mguessan/davmail#122.