Not a concrete answer but some relevant information. Ask your rabbi for a final answer.
R. Dovid Zucker & R. Moshe Francis, Chol Hamoed (revised edition), pp. 90-91:
With the advent of modern technology, new questions have arisen with regard to writing on Chol HaMoed. One such area involves the use of a computer. Inputing data into a computer where the letter appears only on the screen is not considered a melachah according to many authorities. Saving information on a hard drive, a floppy disk or a CD is permitted according to many authorities. Some authorities prohibit the saving of information except for a festival need or to avoid a loss... E-mails, e-faxes, and text messages may be sent on Chol HaMoed provided they are not printed out.See also R. Yekusiel Farkas, Chol Ha-Mo'ed Ke-Hilkhaso 7:98.