Skype now available for Outlook.com for users in the UK
Microsoft has built in Skype to its Outlook.com webmail service.
The move allows users to make audio and video calls and send Skype instant messages via the website once they download a browser plug-in.
UK-based customers are the first to be offered a "preview" version of the technology. Germany and the US will follow "in the coming weeks".
However, analysts questioned whether the effort would help Microsoft regain ground lost to Google's Gmail.
"With Skype for Outlook.com, you can choose the right medium for your message, whether it is an email, call, video call or instant message," Skype said in a blog post.
"You can connect with your Skype and Messenger friends all in the same place."
Microsoft announced an overhaul of its webmail service in July 2012.
The firm has begun shifting away from its Hotmail webmail brand - which it has used since acquiring the product in 1998 - by encouraging users to upgrade their accounts which are subsequently renamed Outlook.com.
It has also shut down its Windows Messenger chat tool in most countries and urged users to switch over to Skype.
Microsoft paid $8.5bn (£5.5bn) to acquire Skype in 2011, buying out eBay and the private investors who owned the service. It remains the Windows-maker's biggest ever takeover.
Adding the service to Outlook.com may encourage users to use the webmail service.
Although its predecessor Hotmail used to dominate the sector, it was overtaken by Google's Gmail last October, according to analysis by net analytics firm Comscore.
Its study - which is based on PC and laptop usage at home and work - indicates Microsoft's market share has continued to slip.
In March Microsoft accounted for 19.7% of global webmail usage compared to Gmail's 20.8% share, according to Comscore. Yahoo Mail came third with 19.1%.
Although the data does not include webmail use on smartphones, the shift can be partly explained by the fact people are increasingly using the devices to check their messages.
That has given Google's suite of apps an advantage thanks to the fact they come preinstalled on Android handsets. Google's mobile platform has proven much more popular than Microsoft's Windows Phone.
"Since Microsoft bought Skype there has been the question: why did they pay that amount of money," said Karin von Abrams, senior analyst at research firm eMarketer.
"This latest move suggests part of the answer is an integrated communications suite, that you are in Outlook.com and can choose whatever kind of tool you want without having to needing to use different applications.
"But I don't think people have had a problem managing the different kinds of messages and calls they are making. If this is more convenient that's great, but I doubt it's enough of a selling point to make people go with Outlook.com rather than other services."
Rival chat apps
Enders Analysis's Benedict Evans said he believed Microsoft's latest move should be viewed as a wider strategy to integrate Skype into all the firm's relevant products. But he too questioned whether the effort would make much difference to Outlook.com's fortunes.
"Skype is huge but it hasn't been setting the agenda for years, arguably since before eBay bought it" he said.
"In the meantime you have rival services like Viber and Whatsapp, which are growing much quicker - there's a lot of people coming up fast on mobile which is where the future is.
"Microsoft is both trying to catch up with all of the stuff that Skype should have done, integrate it with all of their products and also try and work out a route forward. Outlook.com is now certainly a good product and every little bit helps, but there's still not a compelling reason to switch from other services."