stat/smtprec is a SAP Parameter attribute which is used to control Max. number of smtp subrecords for one statistic record information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
Max. number of SMTP Statistic Subrecords in a kernel statistic record
See SAP Parameter Documentation for full SAP documentation for this profile parameter.