If it is an affiliate link, safest practice is to also have a disclosure. What harm does it do? However it does keep you protected should someone decide to report the email. Yeah, that's a long shot, but the FTC often looks for small folks to use as examples for other small folks.

I would always advocate having a disclaimer on your website. Your emails are going to send prospective buyers to your website so that is where the disclaimer needs to be.

Derek

You do need an affiliate disclaimer on your website. Your promotional e-mails are part of your site and therefore I do not
see any reason for including a disclaimer on your e-mails.
I just see this as a practice done with sellers on Amazon and ebay.
Michael

Interesting question.

I would have a standard affiliate disclaimer on your website and then if there is any comeback down the line you can always point to it.