SOLVED !!! found this doc about setting SparkPost (i referred to a different one previously)
quote:
" To add the DKIM record to your DNS, first copy the “Hostname” portion provided in the Set Up For Sending section of the SparkPost UI and paste it in the “Host” section of your DNS TXT record. This value should be similar to scphxxxx._domainkey.yourdomain.xxx . Please note that some providers are particular about the “Host” and may require that the value be added as just scphxxxx._domainkey "
apparently… for namecheap… the value must just be scphxxxx._domainkey
thanks for all the help 