In the mid-2000s, link-exchanges were a popular way for travel websites to try to game Google's search engine results.
Even to this day, travel blogs and websites of any size still receive daily requests for link-exchanges.
Yet the appeal of this link building tactic has waned in recent years. Google and Bing have gotten wise to the strategy, and the value of the resulting pages and links tends to degrade over time.
In light of this, most major brand travel sites no longer consider it a best practice to seek out link exchanges.
Or at least so we thought.
Last week a Tnooz reader tipped us off to a link exchange request they had received for CheapOAir, the respected US-headquartered online travel agency.
The message, which came from a CheapOair.ca e-mail address and gave a mailing address in Ontario, is here:

From: [Redacted by Tnooz]
Date: Fri, Mar 15, 2013 at 7:20 AM
Subject: Link Exchange Request
To: [Redacted by Tnooz]
Hi,
I came across your site [Redacted] while browsing some travel sites. I must say you are doing a commendable job.
I am a blogger & maintain few travel blogs. Some of my blogs are:
[Redacted by Tnooz]
At present I am working with CheapOair.ca. Our sites can be useful to one another. So, I offer you a partnership.
I have some options for you.
1. I could cover you on my blog and in return I would like a back link for my website from your blog within the content.
2. If you allow guest blogging I would be glad to write a blog post as a guest blogger. Within the post there would be a single link to my website.
3. We both can do guest blogging for each other where we can add links to our respective websites.
4. On top of giving link from my blog, I can also give you some links from other websites that I am managing.
Let me know your views soon.
Thanks,
[Name and address, Redacted by Tnooz]
CheapOair distances itself
A second email has been sent to a different Tnooz tipster, who also runs a travel site. Interestingly, this one came from an email address at @cheapoair.com itself with a mailing address for the parent company, Fareportal's, New York City office.
Despite that identification, there is reason to think the email was actually sent from a contractor described as an "SEO Executive at Fareportal" working in or near New Delhi, because of related information Tnooz has obtained.

---------- Forwarded message ----------
From: [Redacted]
Date: Mon, Mar 11, 2013 at 10:54 AM
Subject: Travel Resource Partnership
To: [Redacted]
Hi,
Dear Webmaster,
Greetings of the day..!!
I am the web master for CheapOair, We are an online international travel booking company providing cheap air tickets to different destinations of the world. To know more about us, please visit CheapOair.com.
Today I had a chance to visit your site [Redacted] It's terrific. The information and services offered on your site would be of great value to our visitors and i believe your visitors would find great value in our site. I am writing to see if you would be interested in Swapping link. Because our two websites are complementary rather than competitive, we see the synergy here as an opportunity for mutual benefit.
You will be linked to one of the following sites:
[Same websites as mentioned in the e-mail sent from the Canadian address]
Or Blog post with unique content related to travel on any of these blog
[Redacted]
Your time is greatly appreciated. Looking forward to your reply.
Thanks and Regards
Ashwin
CheapOair
213 W 35th Street,
New York, NY 10001 USA
We asked CheapOair for comment. Pete Howard, CMO at Fareportal, parent company of CheapOair, responded by e-mail:

It is not CheapOair policy to send out this type of request.
Our team members are continually educated and trained to comply with industry-standard best practices, which this communication does not reflect.
CheapOair’s content marketing efforts continue to drive niche traffic, but our strategic purposes are not being advanced unless our team members are following the guidelines we set in place for our marketing outreach programs.
We appreciate you contacting us, and will be following up to ensure that our team members both in the US and abroad maintain proper marketing outreach practices.
So what *are* the best practices in linking?
After all, the theory behind this search engine optimization (SEO) tactic is, essentially, that two sites on the same travel topic that link with each other may be receive greater weight in Google's algorithms than links between sites with no common subject, which may not seem authentic.
The ideal content marketing is to create great, authentic content, and to promote it so that there is a lot of organic interest from others, who will then link to your site.
For more subtle tips, check out this list of linking tips from Search Engine Land. See also what Leo Widrich at Buffer.ly has done with content marketing, as an example.
NB: Image courtesy of Search Engine People Blog on Flickr/Creative Commons.