Despite all the advancements in technology, billionaire investor Mark Cuban, 66, spends most of his day reading and responding to emails.

During a conversation with Business Insider on Wednesday, Cuban revealed that he receives “700 to 1,000 emails” daily via his Gmail account. To handle this, he utilizes three phones: two Android devices and an iPhone.

“I spend most of my day trying to get my unreads under 20,” Cuban told BI.

He highlighted the benefits of email being “asynchronous,” allowing him to reply at his convenience from any location worldwide. Email is also widespread since “everyone” has an email address. Additionally, replying is “fast,” thanks to Google’s automated response suggestions, according to Cuban.

Cuban maintains his inbox orderly by using folders and has “never” contemplated hiring assistance for email management. He steps away from his inbox for an entire day or more only in “extraordinary situations, like a special event for a family member,” he shared with BI.

Cuban says he uses his unread emails as reminders of what he needs to get done that day. He only uses AI to write the autoreply messages, preferring instead to personalize longer emails and noted that he would rather process emails than sit through “long, boring meetings,” or send a Slack message or text because he can quickly search through emails years later.

“I have emails going back to the 90s,” Cuban told BI.

^{Mark Cuban. Photo by Julia Beverly/WireImage}

Still, using Gmail could pose a cybersecurity risk. Cuban’s Google account was hacked in June 2024 after he received a call from a fake Google employee. The bad actor said that Cuban’s Gmail had an intruder and faked Google’s recovery methods to receive the credentials for the account. The hacker got access to Cuban’s email and locked him out.

The hacking hasn’t stopped Cuban’s love of email, however.

Cuban rose to fame as an investor on ABC’s “Shark Tank” for the last 15 seasons, appearing in his final episode in May. He told CNBC that same month that he invested about $33 million in businesses during his time on the show and received $35 million in cash returns. He holds equity in those businesses that are now worth at least $250 million, he disclosed.

Cuban’s first entrepreneurial venture was MicroSolutions, a software reseller that sold PCs, software, and training to businesses. He grew the company to nearly $36 million in annual sales and 80 employees before selling it to CompuServe, a subsidiary of H&R Block, for $6 million in 1990.

Cuban then founded AudioNet, the first video streaming company in the world. The startup, which became Broadcast.com, was sold to Yahoo for $5.7 billion in 1999, making Cuban a billionaire.

In 2022, Cuban co-founded Cost Plus Drug Company, an online discount pharmacy that delivers more than 2,300 prescription medications.

Cuban is now worth $8.6 billion, according to the Bloomberg Billionaires Index.

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