I got a complain from email user that they did not receive email from some of their contact. I guessed it must be caused by spam filter in the mail server. I hosted company’s email at ISP. ISP’s webmail also did not have a Bulk folder, so email suspected as spam will be permanently deleted. Therefore I move all emails to GMail and use their Google Application service.
The problem came when I need to access email from several mail clients. They did not receive all messages, only a part of it. The solution can be achieved from help center. For a short, you just need to set POP username from: firstname.lastname@example.org to recent:email@example.com and set leave all messages in the server. “Recent:” prefix is to fetches the last 30 days of mail, regardless of whether it’s been sent to another POP client already.
That’s all. User now can check spam messages (what?) and download email using POP without problem.