Sending a JSON message in body text of email, strings broken in midstream
if your email client can do html emails you can wrap the code in <pre></pre> tags
Seems to work when sending a html email to my gmail account of json. The json text will look like it breaks but when you go and copy and paste the json into like an editor or even the console it pastes correctly and can be executed. Least it did when I tested using Chrome with GMail as the email client.
Emailed with <pre></pre> tags
Alternatively you can wrap the json in <div></div> or whatever tag and set an inline style of white-space:nowrap; which will put the whole json on one unbreaking line.
Emailed using white-space:nowrap
Of course this is dependent on the email client's capabilities like supporting html and/or css.