Derek Johnson, from Gloucestershire, admitted 16 offences relating to girls aged between 13 and 16.
It follows the collapse of a trial, involving serious sexual allegations, in its fifth week.
The Attorney General's Office will consider whether Reece Galbraith's jail term is too lenient.
The Meriden and Solihull East MP says he has written to the Attorney General over Daniel Clarke's jail term.
Prosper is currently serving a minimum of 49 years in prison for murdering three family members.
The solicitor general says Simon Vickers' life sentence with 15-year minimum term "appears lenient".
The Attorney General said there was "no realistic legal basis" for an appeal over the sentence.
The trial of Axel Rudakubana, 18, is due to begin at Liverpool Crown Court on Monday 20 January.
The emails, sent while she was attorney general, could amount to a breach of the ministerial code.
