Apple has reportedly begun the filtering of outbound messages sent via its MobileMe service.

The fruity one has applied inbound filtering to inbound emails as a precaution against spam since last year. Last month, however, it began filtering messages that users sent using the service – for questionable reasons.

The upshot is that whatever email client a MobileMe user uses, their message will be blocked without notification, reportedly even if the offending content in question contains mild political criticism.

Reg reader Mike Conley, who was the first to tell us of the problem, said that one of three offending messages he sent was blocked because it mentioned the phrase "growing hostility against Frankfurt and Brussels". An email about civil unrest in Greece about the sovereign debt crisis/austerity budget was also dropped. Conley realised there was a problem because he sends messages to himself via bcc. He complained and one of the offending messages was transmitted only for the problem to reappear days later.

As a result, Conley has decided to stop using the service after having been a loyal fan for more than 10 years.

Conloy started a thread on the problem on an Apple user forum. The post was picked up by Reg reader Harris Upham, who confirmed that censorship seems to be taking place.

"I have a mobileme account myself, and I have tested this myself and I'm now convinced that mobileme is censoring outbound mail based on message body content," Upham told El Reg.

Generally speaking we're much more inclined to attribute this sort of thing to a technical screw-up rather than a deliberate policy. The alternative is truly chilly. All-American firm Apple has decided to censor political debate occurring via email for reasons unknown, exactly the sort of behaviour routinely practiced in China and roundly condemned across the political spectrum in the West.

It's very likely there's some innocent explanation to this, but since Apple consistently refuses to speak to us on information security, we don't know what this might be. Enterprise email security firms we asked were unable to shed much light on the behaviour, presumably since it is restricted to Apple's user-base and only visible internally. ®