my email hacked

[eltyar]

dear professionals,

someone is knows everything about my mail and for example when i send one mail to one of my customer with an invoice attached contains my bank details suddenly my costumer telling me is my bank details is changed and when he forward that email with wrong bank information to me i found the sender is not me but someone created same email as my email in outlook.com with a little different letters.

the big question is how he (hackers) catch my scanned invoice before my customer receiving it and changed my bank details with Photoshop or something else and sent it again to the customer !!!!????

note: i'm sending this mail using internal outlook 2013 on my PC. and this case happen with two of my customers and the invoices sent for this two customers from 2 different PCs !!

[Chrispcritters]

I suggest that you immediately scan all your computers for viruses and malware, make sure the operating system is up-to-date, and then change all your passwords.

[eltyar]

any suggesting for a program to do that ?

[lisati]

There are many good tools around that can help track down and deal with viruses and malware. On Windows, I use the free version of AVG.