The Free On-line Dictionary of Computing (19 January 2023):

shitogram

   /shit'oh-gram/ A *really* nasty piece of e-mail.

   Compare nastygram, flame.

   [Jargon File]

   (1994-12-21)


The Jargon File (version 4.4.7, 29 Dec 2003):

shitogram
 /shit'oh·gram/, n.

    A really nasty piece of email. Compare nastygram, flame.