Broadband internet service provider Comcast temporarily prevented its subscribers from sending emails to Hotmail and MSN accounts.

For three days, users trying to send messages to the Microsoft owned internet service received error messages stating: "The message could not be sent because one of the recipients was rejected by the server."

A spokesman for Comcast did not return several requests seeking further information. Comcast operates as a US cable TV provider. Its broadband internet business has 7.7 million subscribers.

The email outage lasted from 18 until 20 October, according to postings by a support agent for the US service on a members-only user forum. Comcast was responsible for the outage, one of the provider's employee by the name of Jason wrote.

The provider blocked messages addressed to Hotmail and MSN accounts because messages to those servers were not being delivered, causing a traffic jam on the Comcast mail server.

"[This] was affecting mail delivery to other domains," Jason wrote. "Since MSN/Hotmail was the only domain that was not accepting email from Comcast, there was little we could do but continue reaching out to MSN/Hotmail (which we did) to investigate this issue and have it resolved quickly."

It occasionally happens that internet or email providers block messages originating from certain geographies or providers because of spam concerns. Jason, however, denied that such a blacklist was used this time.

"During discussions with MSN the issue is being identified as a volume-related issue that has nothing to do with spam," he wrote.