If you find that an email attachment is blocked due to its content or type, which is very common when attempting to send some code or a zip file, the following PowerShell may help:
#create file to send
$source_zip = 'C:\temp\yourfile.zip'
$file_to_send = 'C:\temp\yourfile.txt'
[convert]::ToBase64String((Get-Content -path $source_zip -Encoding byte)) | Out-File -FilePath $file_to_send
#extract zip
$file_received = 'C:\temp\yourfile.txt'
$extract_zip = 'C:\temp\yourfile.zip'
[System.Convert]::FromBase64String((Get-Content $file_received)) | Set-Content $extract_zip -Encoding Byte