将一份正式的邮件进行编辑，将其中所有的错误（包括语法、拼写、标点等）进行修正，并将所做的修改列出来。
邮件内容：Dear Mr. Johnson, I hope this email finds you well. I am writing to inform you that the board of directors have approved our proposal for the new marketing campaign. They believe that it will be highly affective in increasing our market share. I will follow up with you in the coming days to discuss the next steps. Best regards, John
Dear Mr. Johnson,

I hope this email finds you well. I am writing to inform you that the board of directors has approved our proposal for the new marketing campaign. They believe that it will be highly effective in increasing our market share. 

I will follow up with you in the coming days to discuss the next steps.

Best regards,

John

Modifications made: 
- "board of directors have" changed to "board of directors has"
- "affective" changed to "effective"