These kinds of emails are not actually sent by legitimate people operating legitimate websites. Instead, they are usually automated and sent by a 'robot' that crawls the web and indiscriminately submits contact forms asking for links. Taking part in these link exchange schemes will not help your site's visibility, and could actually cause some serious damage.
The emails will usually read something like this:
Dear Sir or Madame,
I came across your site and couldn't help but notice that your site is a quality site and I think that my visitors would enjoy seeing it.
Would you be open to linking to my site in exchange for me placing a link to your site on mine? It would benefit us both!
Just add this code,which contains a link to my site embedded in a small image, to your site and I'll link back to you right away. Please do it now.
Why would you get an email like this?
Unfortunately, as a site rises in search engine rankings, in addition to becoming more visible to potential customers, it also becomes more visible to robots programmed to crawl the web for various spam marketing purposes. One use of these robots is to fill out contact forms on websites and ask for links.
Image from Geeky Gadgets.
What are Reciprocal Links?
Reciprocal links occur when two websites link to each other. So, if site A links to site B, and site B links to site A, the links are reciprocal links. A one-way link occurs when one site links to another, but the site that is linked to doesn’t link back. So, if site A links to site B, but site B doesn’t link to site A, the link on site A is a one-way link to site B.
Google considers the links pointing to a website in determining that website’s position in its results. While this is a bit of an oversimplification, you can think of it like this: each link from an outside site is seen as a ‘vote’ for a website. The more votes a site has, the better the chances of it showing up in a prominent position in Google’s search results.
Because you are providing something in return, a link in this case, a reciprocal link is viewed by Google as less valuable than a one-way link. In Google’s eyes, a one-way link is closer to an actual vote for a site, since one site is linking out without getting a link in return. Because of this, Google’s algorithm for determining it’s search results gives much more weight to one-way links. One step beyond not helping a site's rankings, a reciprocal link that links to a site that Google perceives as 'shady,' or having too many reciprocal links leading to unrelated sites can actually hurt a site's rankings.
For these reasons, it's best to avoid email requests looking for an exchange of links. If a legitimate website owner writes a personal email asking you to link to their website, and you feel that it would actually benefit your visitors, it's fine to link to it. But, always choose not to exchange links with a robot!
If you'd like to learn a little more about one way to get links to your site that will help your search engine rankings, see my colleague John-Henry's excellent post about link building with original content.
Roger Panella is a former SEO Analyst at Digital Third Coast, a digital marketing agency based in Chicago. You can find Roger on Twitter and Google+. Connect with Digital Third Coast on Google+.