Most managers receive over 100 email messages per day, and spend only a second or two deciding whether to open them. Most such decisions are based on the subject line. Even when they open the message, they may only read a line or two before deleting it and going on to the next one.
If you take the time to send an email message, take the time necessary to insure it fulfills its purpose. For instance, craft the subject line so it grabs their attention while telling them what the email message is about. Put the vital information in the first few lines and be clear and direct about what you want them to do after reading the message.
Proof the message before sending it, correcting any typos and bad grammar, and tightening up the sentences. It may take longer to write shorter messages but they will get better results. Avoid attachments if possible. Instead, cut and paste the additional information at the end of the message. Make it is easy for the reader. Their time is just as valuable as your time, and you are the one who is initiating the interruption.