When I started querying agents, I learned the hard way that pasting parts of my manuscript directly from a Word document into an email message wasn’t the way to go. Many agents ask for a few sample pages, and the first queries I sent out had jumbled and weirdly formatted text. Not the best first impression, huh?
Eventually, I came up with a method that seemed to work. I’m not saying this is the best or only correct way to do things, but it worked for me.
1. I switched my email format to plain text. Yes, this will get rid of your ability to show italics or underlined text. But it’s also a format most widely read by email programs.
2. I created a text file (.txt) for my query. (For Mac, I used TextEdit to do this.) I originally wrote it in Word, so I pasted the text from there into my text application. I kept the text single-spaced, and then I added a double space between paragraphs. I didn’t indent new paragraphs.

3. I copied the first 50 pages of my manuscript. (You will most likely be asked to paste 5-10 pages into the body of the email, but yes, some agents do ask for as many as 50 pages.) I pasted these pages into a new text file. Just like the query, I kept the text formatted as single-spaced, and I added a double space between paragraphs. And again, no indentations.

4. I did the same thing for my synopsis.
5. For every query, I opened these text files and pasted in the query followed by whatever the agent requested for their query submissions (synopsis, sample pages, etc.).
By using these text files, you’ll only have to format the text once instead of doing it every time. Keeping in mind you’ll have to update these text files if you make changes to your manuscript. Also, make sure you send a test email to yourself before you query, just to double check the format.
Hope this helps!