First I'd check with my ISP (internet service provider) to see if they know of any reason for this.
If your ISP is no help, then I'd download and install MalwareBytes, get it up to date, and do a scan with it.
If you're still having problems, I'd boot to Safe Mode and do a full system scan with your anti-virus program.
If none of the above works, I'd create another email account as a stopgap until you can get a computer expert to look at your system. Gmail, MS Hotmail, AOL, etc. all offer free email accounts.
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Good luck.
I am a lawyer in MA. I have multiple e-mail addresses and my paralegals all have at least one business e-mail address. For a number of years I have been working with someone in CA with respect to medical issues or concerns of clients or client cases. For the last week or so, all e-mails sent to any of my e-mail addresses as well as that of the paralegals has not been received. At the other end there is nothing to indicate not being received. My main e-mail address provider suggested I may have by mistake blocked, but I did not and checked the block list. No idea what is wrong or how to fix. San Francisco has prepared a memo for client consumption that attempts to send to now four different e-mail addresses have failed. Any suggestions or ideas will be most appreciated.

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