If the correspondence is harassing, or threatening, blacklisting is appropriate.  However, makes sure it really is.  Alas, some women have a hair trigger.  In my early hobbying days, I knew there was a good chance of being sent to another city for a week.  Well, I went to handy dandy TER, did some research and saved the URLs of the personal web site of three of the ladies I might want to see.  Three months later, I was being sent.  I relooked at the web sites, choose the lady who seemed most promising, and filled out her web form with two references.   I got an email back asking how she found me.  I had not relooked at her TER page.  She had gone under the radar, and delisted her self from all escort sites.  Her personal page was still up.  I wrote back that I had saved the URL of her web site on my FireFox three months ago in a candidate list. She wrote both of the references I provided that I was a stalker who maintained a hooker list.  Took a bit of doing to mend fences with both ladies.  Once they realized what happened, they got a good laugh.  Needless to say, number two was engaged on that trip, and my world was rocked.