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1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsA few keystrokes can turn an ordinary email into an accidental disclosure: a mail app suggests a familiar-looking address, someone selects it, and sensitive information goes to the wrong recipient. Serguey Shinder describes this as the most common data-breach pattern in his organization, but his figures are a single organizational account—not a ranking across organizations.
How autocomplete turns a routine email into a breach
Email services can predict an address from the first characters typed into the To or Cc field. When several people have similar names—or an old external contact appears alongside a colleague—the suggested entry can look right at a glance. Selecting it sends the message to that address, even if the sender intended someone else.
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The exposure can be more than the email text. Attachments may contain personal information, and a message intended for a specific individual may reveal private details to an unrelated recipient. Verizon’s earlier sector analysis defines misdelivery as sensitive information reaching the wrong recipient and includes autocomplete as an example; it also discusses mismatched contents in mass mailings. Verizon’s 2020 sector analysis explains the mechanism, not current prevalence.
What Shinder’s incident figures do—and do not—show
Shinder says his organization recorded 34 personal-data incidents in the preceding year. In his account, 32 involved email sent to the wrong person, and 27 of those involved accepting a suggested recipient after typing the first few letters of a name. He gives examples: a disciplinary letter sent to a similarly named external contact, a customer statement sent to a competitor, and a spreadsheet containing workers’ home addresses sent to an external list. He says three incidents were reportable. The account does not clearly identify the year of those counts, and it does not provide an independent audit or detailed methodology. These are figures from his organization, not a general rate or proof that autocomplete is the leading cause everywhere. Shinder’s account
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How the account fits broader breach data
Verizon Business’s 2024 Data Breach Investigations Report says misdelivery accounted for more than 50% of errors in its 2023 dataset. That percentage is of errors in the report’s dataset—not of all data breaches. The report also attributes 87% of errors in that dataset to end users, a finding about its collected and classified cases rather than a universal measure of employee behavior. Its miscellaneous-errors summary lists 2,679 incidents, 2,671 of them with confirmed data disclosure; those counts describe that report’s pattern set, not all incidents worldwide. Verizon’s 2024 report
The two sources provide different kinds of evidence: Shinder describes one organization’s experience, while Verizon reports patterns in its own dataset. Neither establishes a universal ranking of breach causes.
Practical ways to reduce misdirected email
No single safeguard eliminates the risk. Organizations can choose controls based on how sensitive the message is, the email system in use, and how much friction a control adds to routine work.
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Make recipient review deliberate
Review the full address—not just the displayed name—before sending sensitive material. Organizations can review how their mail clients handle remembered external suggestions and consider removing or limiting those suggestions where appropriate. A clear confirmation step for messages with external recipients and attachments can add a pause at the point where a mistake matters.
Build in time to catch a mistake
A brief outgoing-mail delay creates a window to cancel a message sent to the wrong person. In Shinder’s account, his organization introduced a 60-second hold. That is a described organizational measure, not evidence that a delay of that length is optimal for every system or workflow.
Keep especially sensitive documents behind sign-in
Instead of attaching sensitive HR or credit-control documents, an organization can place them in an authenticated portal and give the intended recipient access. This can limit exposure compared with sending a downloadable attachment to an address, but it depends on access being correctly assigned and managed.
Consider protecting message contents
Encryption can help prevent an unintended recipient from reading message contents. A regulator case study involving a complaint letter attached to an email sent to an incorrect address identifies encryption as one possible protection. Encryption does not fix a wrong recipient selection, and it does not remove the need to assess what happened. The regulator case study
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What the reported outcome says about safeguards
Shinder says his organization removed remembered external suggestions, added a confirmation step for messages with external recipients and attachments, introduced a 60-second outgoing-mail hold, and moved sensitive HR and credit-control documents to sign-in portals. He reports that misaddressed messages fell by about two thirds in six months. That is a self-reported before-and-after outcome; the account does not describe a controlled evaluation, so it cannot show how much of the reduction any one control caused. Shinder’s account
When a misdirected email may require breach notification
Sending personal information to the wrong email address may amount to a personal-data breach, but notification duties depend on jurisdiction and the circumstances. Ireland’s Data Protection Commission describes an email predicted from the first characters entered and sent to the wrong recipient as a common breach scenario. Its guidance says that when an incident is likely to pose a risk to data subjects, the organization must notify the Commission under Article 33(1). This is Ireland/EU guidance, not universal legal advice; organizations should follow the rules that apply where they operate and assess the specific incident. Ireland’s Data Protection Commission guidance
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