We have a blog discussing products of a variety of manufacturers. Recently a manufacturer asked us if we could utm tag links from our blog to his site with the tags utm_source=OurSiteName&utm_medium=site&utm_campaign=OurSiteName.

Since the manufacturers can already see our traffic in his referral traffic report, I do not see the point of adding utm tags to all our outbound links to manufacturers but perhaps I am missing an important point, so: is there an advantage of tagging outbound links with utm tags instead of just leaving the traffic to appear in the referral traffic section of the receiving website (eg is the referrer information in HTTP requests less reliable than utm tagging,...)?

Many thanks in advance,

Peter

We have a blog discussing products of a variety of manufacturers. Recently a manufacturer asked us if we could utm tag links from our blog to his site with the tags utm_source=OurSiteName&utm_medium=site&utm_campaign=OurSiteName.

Since the manufacturers can already see our traffic in his referral traffic report, I do not see the point of adding utm tags to all our outbound links to manufacturers but perhaps I am missing an important point.

Is there an advantage of tagging outbound links with utm tags instead of just leaving the traffic to appear in the referral traffic section of the receiving website (eg is the referrer information in HTTP requests less reliable than utm tagging,...)?