RFR: Parse older conversations, but only the most recent messages

[Robin Westberg]

Hi all,

Please review this small change that allows the mailing list bridge to parse older conversations, but filters out
individual old messages. This will allow bridging of conversations that are longer than 60 days, but still avoids
unnecessary checking for already bridged messages.

Best regards,
Robin

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Commit messages:
 - Parse older conversations, but only the most recent messages

Changes: https://git.openjdk.java.net/skara/pull/498/files
 Webrev: https://webrevs.openjdk.java.net/skara/498/webrev.00
  Stats: 5 lines in 2 files changed: 3 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/skara/pull/498.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/498/head:pull/498

PR: https://git.openjdk.java.net/skara/pull/498