The email specification says that the line length of an (HTML) email should be no longer than 998 characters.
When Preside sends an email, the HTML body may have content in one, long, run-on line.
While most email services (Gmail) handle this gracefully, and insert a line break at the last white space before that 998 char limit, others (Outlook 365) will simply insert a line break at the limit - which will display on the user's screen as an extra space per haps in the mid dle of a wo rd.
The solution is to manipulate the HTML body before sending. A good solution is to insert a line break in place of the first space after each 200 characters on a line.