Above all, I think leaving an email record is a good point.
More than anything, I think emails leaving a record is good point.
「なによりも、emailは記録が残ることが良い点だと思います」= Above all, I think leaving an email record is a good point.
「なによりも」= above all (else); more than anything (else)
「emailは記録が残ること」= emails leave a record
になります。