return lists of mailings. 🔓

returns lists of mailings according to following filter settings<br/> <br/> <strong>NOTE:</strong> The <code>start</code> and <code>end</code> fields depend on the <code>state</code> field.<br/>   - finished mails are filtered by finished time<br/>   - draft mails are filtered by creation time<br/>   - waiting mails are filtered by the time they will be sent<br/>   - running mails are filtered by the time they have been started<br/>