It appears that Scheduled Jobs for sendmail is throwing memory errors. After it was observed that mail was not sending, I attempted to "Execute Now" from the admin area.
Fatal error: Out of memory (allocated 120848384) (tried to allocate 21703932 bytes) in /home/[site]/www/www/sites/all/modules/civicrm/packages/Mail/mimePart.php on line 313
My host increased my memory, "We just increased your account's memory limit from 195 MB to 295 MB. We applied the changes in your global php.ini settings as well."
Now the error reads:
Fatal error: Out of memory (allocated 203685888) (tried to allocate 29831950 bytes) in /home/[site]/www/www/sites/all/modules/civicrm/packages/Mail/mime.php on line 1030