When I first heard of Sparrow, a new email client (in beta back October 2010) that used the IMAP protocol and promised to be good, minimalist e-mail interface, I was indeed interested in finding more about it. At the beginning you could only use it to read GMail, but eventually it started supporting providers, including even Exchange.
I was not particularly horrified by its acquisition by Google, but I was a bit sad to see that the move meant that they would not update or change the application. There was even that petition asking Google to “keep Sparrow alive”. Anyway, after the taken over took place, I found that suddenly some bit and pieces were not working as they had been. One that has been an annoying one, was the fact that some accounts would take forever to download mail and particularly the fact that when quitting the application, it would just get zombified, i.e. Sparrow would not quit and I would have to Force Quit the application.
I have now managed to sort that problem. I am not sure if this was an issue with my Exchange server or indeed a bug in Sparrow, but now the application is happier than it was for a long time (and me too!). The issue was with a particular Exchange account, more specifically with the SMTP server. For some reason, Sparrow did not like the settings that seem to be working fine in Mail.app or Thunderbird. So, here is what I did:
I deleted the account and started afresh setting it up, when asked for the SMTP server details, I made sure that the “Secure Connection” option was left unticked and that the Port was the one specified by my provider (in this case Port 25 – see figure below). That has made the application to work and exit fine. If you are having a similar problem, I hope this helps.