After Edward Snowden’s revelations about the NSA, many people have become far more careful with their online privacy and data. Businesses, journalists, and other users who handle sensitive information have long relied on encrypted email to prevent leaks that could cause serious damage if intercepted. That is why it is particularly concerning when an internet service provider blocks encrypted mail traffic without notice.
Engineers at Golden Frog, a digital security and privacy company, discovered they were temporarily unable to send encrypted emails over Cricket Wireless’s mobile network.
Golden Frog described the situation as a threat to the principle that internet traffic should flow freely across networks.
The company raised the matter in a filing to the Federal Communications Commission (FCC) in July, and technology site Techdirt reported on the problem shortly afterward. Follow-up tests conducted after Techdirt’s article appeared indicated that Cricket had removed the restriction.
Cricket did not proactively notify customers about the blocking or explain the cause, and it remained unclear how many subscribers may have been affected. In a comment to The Washington Post, Cricket said it was “continuing to investigate the issue but do not intentionally prevent customers from sending encrypted emails.”
Normally, when a user sends an encrypted email the sender’s mail server attempts to establish a secure connection by checking with the recipient’s server to confirm it can accept the encrypted transmission. According to Golden Frog, in this case Cricket’s network prevented the process before that handshake could occur: the encrypted message was stripped of its encryption request and never delivered to the receiving server for authorization.
Golden Frog traced the problem after one of its engineers, who lived in rural Texas and relied on Cricket’s service, repeatedly failed to deliver encrypted messages. Investigation showed those emails were being forced through a legacy submission port—Port 25—which many ISPs block because it is commonly abused by spammers. In this instance, however, the result was that encryption negotiation itself was being disrupted.
This incident adds fuel to the broader net neutrality debate, which has intensified as some ISPs push for ways to prioritize or throttle traffic based on who pays for preferred treatment. In its FCC filing, Golden Frog argued that blocking or altering encrypted traffic undermines the expectation that internet communications should traverse networks without interference.
For users who depend on secure email—whether to protect corporate secrets, journalistic sources, or personal privacy—any interference with encryption negotiations poses a real risk. Transparent policies and clear notifications from providers are essential so subscribers understand how their data is handled and can take alternative measures if necessary.
Do you think ISPs should be allowed to block or interfere with encrypted traffic? Share your thoughts in the comments.