Google provides a 'free' email service for those brave enough to use it knowing their email's are read and absorbed by Google to better create a profile of the user based on who they email, about what and of course what email's they receive.

Because its 'free', this service is a clear target for spammers who, with some scripting can create a large number of these free accounts automatically, and then leverage these to send spam. When you think about it, there's not really anything Google can do to stop this other than make a charge, but its 'free' so that's not going to happen.

The traffic created by these spammers doesn't go un-noticed and the servers that are sending the spam, i.e. Google's email servers are quickly blacklisted. This will of course mean that the blacklisting will affect all Google's free email users, but that's the price you pay for using 'free' email and you cannot expect it to be commercial grade.

We know that Google has a fair number of servers which load balance the sending and receiving of email, and this means that at any one time, a good percentage of these servers will be blacklisted meaning that 'most' email will be blocked, but Google transfer email's between the servers on retry which results in some email making it through.

Blacklisting generally lasts 24 to 48 hours after which time it will expire *IF* the deluge of spam has subsided. Since Google is constantly being leveraged to send spam there will always be blacklisting in effect on some servers.

This isn't a problem for business and corporate customers since they tend not to receive, or want email from 'free' email accounts and in fact some customers ask us to block all free email as a policy which we can do. For those residential customers unwilling to spend a few pounds a year on a commercial email product, blacklisting and intermittent delivery and reception are just part of the landscape and it affects all free email providers to some degree.