I had quite a few sales expire in the Exchange and received e-mail. I was able to collect some of the duty officers but others did not appear in my roster when I chose "take items" from the mail message. They disappeared from the mail attachment and are nowhere to be found in my roster, which still reads 170 of 175. So, it had nothing to do with running out of space. After losing the first officer, I closed out all my open windows in the game and went back to the Mail terminal. I thought it was OK because I started getting the others, but then, later, when I tried to retrieve other officers, I lost five in a row.