It is important to note that the listening capabilities for Twitter in Meltwater Engage differ from the listening capabilities for Twitter in Meltwater.
The Twitter data in Meltwater Engage is delivered via a firehose directly from Twitter. This means Meltwater Engage has full access to all historical data on Twitter, regardless of when the search is created.
This also applies to historical data for sent messages. When you sync up your Twitter profile with Meltwater Engage, you will be able to see every message you've ever sent in sent messages (prior to the contract with Meltwater Engage) and see all historical conversations for any users you have conversed with in the past. The listening component will pull back all historical content in the last 30 days (which is a Meltwater Engage enforced limitation, not a capability limitation).