2 added 8 characters in body
source | link

The Nielsen Norman group have done some thorougly newsletter reasearchthorough newsletter research and written a 600 pages report (not free) on the topic:

http://www.nngroup.com/reports/newsletters/

The Nielsen Norman group have done some thorougly newsletter reasearch and written a 600 pages report (not free) on the topic:

http://www.nngroup.com/reports/newsletters/

The Nielsen Norman group have done some thorough newsletter research and written a 600 pages report (not free) on the topic:

1
source | link

The Nielsen Norman group have done some thorougly newsletter reasearch and written a 600 pages report (not free) on the topic:

http://www.nngroup.com/reports/newsletters/