What is an E-Mail Storm?

Mary McMahon

An e-mail storm is a situation where people start hitting “reply all” on e-mail messages sent to a group, causing a dramatic uptick in the number of messages handled by a server and leaving individuals with in-boxes laden with messages. While an e-mail storm can be a topic of humor or irritation, it can also potentially pose a problem, as servers may become so overloaded that the deluge of e-mail effectively creates a denial of service attack, shutting down the server. For this reason, steps are usually taken to prevent e-mail storms.

Man holding computer
Man holding computer

Most commonly, an e-mail storm is associated with a listserv, a group of people signed up to an e-mail service. People can send messages out to everyone on the service with important information or correspondence, and individuals on the list can read these messages, reply to the sender, or choose to reply to all, sending a message to everyone on the list. People may hit “reply all” by accident and trigger an e-mail storm as infuriated subscribers respond to inform them that they didn't need to send the message to everyone, setting off a firestorm of e-mails.

This can also occur when a controversial matter comes up and everyone on the service wants to weigh in. Rather than sending messages to individual people and carrying on a private conversation, people start replying to everyone, creating an e-mail storm. People not interested in the discussion may send messages to everyone as well, pleading with people to stop e-mailing the entire service. When a service includes hundreds or thousands of subscribers, the server can quickly back up.

During an e-mail storm, handling of other messages on the server can slow to a crawl. Individual people caught up in the storm can have trouble accessing their inboxes, and it may take a long time for messages to load. Messages not related to the storm may be hidden under a pile of new messages from the e-mail storm, making it difficult for people to find correspondence they need to see and respond to.

In 2009, an e-mail storm at the US State Department actually resulted in threats of disciplinary action, with officials warning that the storm compromised servers and potentially exposed the names of officials working confidentially. Workers were warned to use the “reply all” option with care, only directing messages to an entire group of people on an e-mail distribution list when it was actually necessary.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a EasyTechJunkie researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


I had a friend who did a newsletter about her life each month and sent it to all her friends and acquaintances. She got my email address from previous correspondence and automatically added me to her newsletter recipient list.

I really didn't care to hear about the cute things her kids did or her various infections and antibiotics. Sometimes, she got so private with the details that her recipients would hit “reply all” just to point out to her and everyone else that this information was too private and we didn't want to know about it.

She got into an argument with someone who did this, and the entire thing was public. People were hitting “reply all” right and left, as though it were a public forum. I had a ton of mail like this to sort through, and I had to make filters to make all the addresses on the list go to my junk box.


@cloudel – It usually isn't the sender's fault when an email storm happens. Unless she replied to all every time she answered a question, she was not to blame.

Email storms are caused by people who either don't know enough about their own email to respond in the correct manner or who want everyone to know their business. They need to realize that a mass email is not meant to be a type of social networking service, where everyone gets to see your comments.

A mass email is for informative purposes only, and it should be responded to privately. Anyone who chooses to make their response public is taking the risk that they will cause a storm and make everyone on the list very unhappy with them.


I got wrongfully blamed for an email storm at my job. I invited forty coworkers to the company barbecue, as directed by my boss. I don't know why most of them wrote back with the “reply all” button instead of just the regular “reply” button, but they did, and it flooded the server.

I made sure to answer each one of them in a private email, but the mass emails kept coming. The server shut down, and we were unable to access our email for the rest of the day.

I encourage everyone to treat the “reply all” button like an emergency exit door. Only use it when absolutely necessary, and be aware that an alarm will sound each time, even if it is only in people's heads.


There was a small email storm at my workplace a few years ago. A coworker sent out an email to everyone in the office that she was throwing a bridal shower for another coworker and we were all invited.

I was fine with receiving this first email, as I'm sure everyone else was. It was the thirty emails that followed that upset me.

Instead of just replying to the sender, nearly every person in our office hit “reply all” to tell her whether or not they could make it or to ask questions about bridal registries. I don't know if they wanted everyone to know that they were or were not attending, or if they just didn't know how to respond to a mass email, but they really cluttered up my inbox.

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