My wife has been using Google Apps Free edition for several years in her small business without any difficulties.
In the last week or so, she has been contacted by two people whom she has received mail from regularly in the past, informing her that when they try to mail her, the mail gets bounced by Google, with a message saying "550-5.7.1 Our system has detected that this message is likely unsolicited mail. To reduce the amount of spam sent to Gmail, this message has been blocked. Please visit https://support.google.com/mail/answer/188131 for more information."
Of the two people that we know have had bounces, one is using a mail address from the domain of a large ISP, the other is using an address with his own domain. Both of them are self employed professionals, not very tech savvy, and very unlikely to have ever done any digital marketing (or marketing of any kind), and definitely not originators of spam. My wife knows of these bounces because they followed up by phone, but there are possibly others who just went elsewhere when they got the bounce notification.
Is there any way for us to prevent these bounces occurring, without upgrading to the paid version? It seems that in the paid version it is possible to whitelist addresses/domains, so I presume that would solve the issue. Can anybody confirm if that is the case?