Microsoft has become the latest tech advertiser to give a shout-out to same-sex marriage with an ad for Outlook that shows two women getting married.

The ad comes after Amazon released an ad last month featuring a same-sex male couple. Expedia — formerly a Microsoft unit — also ran an ad last October showing a father coming to terms with his daughter's decision to marry another woman.

Hayes Roth, chief marketing officer with branding firm Landor Associates, compared the sudden ubiquity of gays in advertising to the late 1950s and early 1960s when African-Americans began being featured in ads.

"It's become mainstream," Roth says.

Nevertheless, even just a few years ago, the conventional wisdom in marketing circles was to avoid bringing up potentially divisive issues like gay rights to avoid alienating consumers. But Roth says that brands can't get away with that anymore: "You can't avoid the topic, so you might as well say where you stand."

Microsoft has hardly been reticent about its support of same-sex marriage. The company (and Amazon CEO Jeff Bezos) came out in support of an ultimately successful bill in Washington State that would legalize same-sex marriage in 2012. Founder Bill Gates also recently advocated for a repeal of the Boy Scouts' ban on gay members and leaders "because it's 2013."

Image courtesy of YouTube, Microsoft