By any measure, the letter a Norfolk woman received from President Reagan was designed to be impressive.

It came on gold-embossed stationery and had a picture of the White House's south--or Truman--balcony.

"Your long and loyal history of major financial support for the Republican Party and your service in the community tells me I have made the right choice by inviting you to join the Republican Directors," said the letter, signed with a facsimile signature of the president. The only requirement to join this "probusiness arm of the Republican Party," the president said, is a $2,500 contribution.

Perhaps the Republican Party should change the source of its mailing lists.

The lady to whom the letter was sent is Betty Howell, a Democratic member of the Norfolk City Council for nine years, and wife of "Howlin' Henry" Howell, surely the most liberal of Virginia statewide officeholders in recent memory. He served as lieutenant governor from 1971 to 1977 and three times unsuccessfully sought the governorship, once winning the Democratic nomination.

Betty Howell could have had some fun in her response to Reagan but, alas, it was deadpan. "Not only have I never voted for a Republican candidate, I have never contributed any money to the Republican Party," she said.