The two companies have been talking for a while, but a deal appears more imminent now, the sources said. Of course, these things are never final until they’re final.

Xobni could be a fit for Yahoo’s mail and productivity tools, as it neatly creates automated profiles for each email contact with correspondence history and social network data.

Xobni has raised more than $40 million, but it has never had massive success. Backers included Y Combinator (where the company was one of the earliest participants), Khosla Ventures, First Round Capital, Atomico, Baseline Ventures and Cisco.

Yahoo declined to comment, and Xobni did not return requests for comment.

Xobni CEO Jeff Bonforte had previously been a Yahoo executive in charge of communications products and social search from 2005 to 2008. Not that the Yahoo of 2008 had much leadership in common with the Yahoo of today, but it would be sort of like coming back to the mother ship.

Way back in the day, Xobni had reportedly walked away from a deal to be acquired by Microsoft for approximately $20 million in 2008.

Since then, Xobni expanded from making just an Outlook plugin to supporting Gmail, Yahoo Mail and iCloud, and it created its Smartr Contacts apps for Android and iPhone.

Meanwhile, Yahoo CEO Marissa Mayer is on an acquisitive streak. She bought a bunch of mobile app companies — though only spent $16 million for the bunch — Summly for $30 million, and Tumblr for $1.1 billion. And there’s persistent chatter that she’s looking at Foursquare, as well.

Dave Morin, CEO of Path, is adamant that he isn’t doing anything wrong. “Path does not spam users,” Morin told AllThingsD in an interview about the self-proclaimed “personal network” yesterday. “Invites on Path are never sent without a user’s consent — any allegations to the contrary are false.”

That’s in reaction to a recent series of complaints about the hyper-growth the San Francisco-based startup has undergone of late, after Path updated its software to goose growth. The change has elicited some public outcry, blogger criticism and accusations of spamming users.

Which leads to the simple question: Can a mobile app be intimate and private while pushing explosive viral user sign-ups?

There’s no question that Path has taken one of the more traveled-by paths as of late. After it plodded along in the low-millions-of-users range for much of 2012 — which, for an app defined by restricting its users’ connections, seemed appropriate — the service has seen a massive increase in sign-ups in just a handful of months.

It has ballooned to 12 million registered users as of today, Morin said, with most of the growth coming from North and South America — especially, as of late, from the U.S.

That growth spurt, Morin said, has been helped by a new onboarding process that encourages a user to “Promote My Path” via social avenues such as Instagram, Facebook, Twitter and Tumblr. In addition, they’re now able to opt in to let Path search their address books, Twitter and Gmail accounts in order to invite new people to the service, be it via email, Twitter or — most aggressively — through SMS text messages.

Here’s the big issue: During the invitation process, check-boxes are automatically marked to send messages to your friends, which means you have to uncheck them in order not to send out invites. Technically it’s an opt-in process to send out those invites, as the user must tap a button to send them out. But for the average user who is not paying close attention and just wants to get to the app, it’s easily something that could be missed — and, ultimately, could feel like Path has spammed your network of friends.

All of these elements combined is a shift for an app that was once the epitome of growth-wary. “Private by default,” the company states on its website, limited to 150 friends (though initially limited to 50), and “designed with the people you love, your close friends and family, in mind.”

The Path of today, however, is not the Path of yesterday, and it has had repercussions.

Until recently, users were able to invite their Facebook friends to join Path en masse, sending out as many invitations as you have Facebook friends with only a few taps of the screen. That was another change from past versions of Path, Morin said, which once used an algorithm to suggest only the closest friends you’d want to connect with.

Facebook severed Path’s invite ability over the weekend, however, in the wake of a dust-up with a U.K.-based user who joined Path one evening before bed, only to wake up and find that Path had sent texts, emails and (inadvertently) phone calls lobbying his friends to join Path on his behalf.

It’s worth noting here that Path needs to tread carefully with address book and personal data of its users; Path settled with the Federal Trade Commission earlier this year, after allegedly violating COPPA regulations on collecting user data from individuals under 13 years old.

Facebook confirmed to AllThingsD that it had cut off its “Find Friends” access to Path at the moment, but emphasized that users can still syndicate content from Path back to Facebook. Facebook did not address whether the restriction came as a result of Path’s recent spamming accusations, and Morin told me he didn’t know why Facebook chose to cut him off when it did.

“We certainly hope that Facebook allows users to connect with their friends on Path and with any other partner applications in the future,” Morin said.

Morin, who is a former Facebook employee, seemed to shrug off his relationship problems with the social networking giant. Along with Path’s rapid growth, Morin said, engagement is higher than ever, and Facebook’s “Find Friends” feature contributed to less than 5 percent of new user connections on Path. What’s more, he added, Path’s most recent update added the ability to find friends from a user’s Gmail and Twitter accounts — through a new partnership with Twitter — effectively supplanting the loss of Facebook’s social graph.

Morin also maintained in an interview that the host of growth-promoting features have been introduced at the request of the users, who have sometimes found other ways to connect to outsiders and promote Path — ways which weren’t originally incorporated into the service. “We’ve learned that if users want to do something, we just want to get out of their way and let them do it,” he said.

“Look at the one-star reviews in the App Store,” Morin said. “Making it easier for people to find friends and help them connect on Path is one of our more common requests.”

It’s legitimate to cater to user requests, of course, if that’s all Path has been doing. “The more tools we give people to invite friends, doesn’t mean they will all join,” Morin said. “The limit of 150 friends in particular actually encourages a thoughtful sort of curation,” he said.

But given the company’s most aggressive pushes yet to expand the service, there’s likely more playing into this than simply user demand.

After three years, for example, with upward of $50 million in venture capital raised from every big venture firm and notable angel investor in the Valley, Path is under intense pressure to show what it has achieved with all its efforts. Until recently, the company has also not yet presented much of a monetization model.

So perhaps when you’re touting a valuation in the hundreds of millions, a strictly “personal network” just isn’t enough.

Within hours of Twitter launching its Vine video-sharing application on Thursday, Facebook has cut off access to Vine’s “find people” feature, which lets used to let Vine users find their Facebook friends using the Vine application.

What does that mean? It’s basically an annoyance, a hindrance on an easy way to connect with all your existing friends using the service. It would have been a good way to jump into a new product, rather than manually trying to find all of your friends using the app.

No comment from Twitter beyond the error message we’re seeing pop up when we try to use the Facebook friend finding feature in the app, and no immediate response from Facebook as of yet.

But the cutoff isn’t exactly surprising, given Instagram recently snipping Twitter cards integration, and Twitter cutting off access to Instagram’s “Find your Friends” feature. Welcome to the new, competitive landscape of social tech companies.

The loser in all of this? Sorry, user, but it’s you.

And yet, contacts still have room to grow. Enter Ringya, an iPhone app which promises to add a layer of context on top of our sprawling lists of co-workers, club members, parent groups and so on.

It works like this: Instead of sorting everyone by name, Ringya files contacts into “rings.” You can share a “ring” with others, meaning the contact info of everyone on the list can be ported from one phone to another in one step.

(Ringya made the list you see to the right before we talked and shared it with me. And no, I have no idea why they gave my co-workers formal prefixes).

Then, if someone who’s sharing the ring adds a new contact, all users will see the new person in the list when they look at the app.

Gal Nachum, Ringya’s co-founder, calls this “inherent virality,” since using the mobile app normally spreads its reach. If a Ringya user shares their ring with someone who’s not a user, the second person gets a personalized text message asking them to download the app.

Unfortunately for some potential users (especially those without iPhones, although an Android version of the app is on the way), this means the organized contact lists are accessible only through the app.

For those who do have the iPhone app, though, Ringya offers a few nifty features. As with the mobile messaging app GroupMe, it’s very easy to contact everyone in a ring at once.

The difference is that while GroupMe lets users text or message each other in-app, Ringya users can contact their lists via a phone call, text message or email.

Especially promising is the context Ringya offers for incoming calls. When someone from one of your rings calls you, Ringya shows whatever info it has about that person (e.g. “Editor at AllThingsD”) before you pick up the phone.

Finally, the app lets users create a new ring by snapping a picture of a paper contact list. This is definitely an effort-saver in theory, especially for organizations with more than a dozen members that don’t put their rosters online. But the import of a short three-person contact list I made took more than 10 minutes to process.

Even with my handwriting, though — which was once generously likened to chicken scratch — all the names and numbers were imported perfectly.

Ringya is a free app available for download from the iOS App Store here.

The free iPhone app now factors in your location so that nearby friends pop up at the top of your contact list. And searching by keyword through your Brewster address book now offers more refined results.

For example, a search for “running” might previously have brought up lists of people who enjoy jogging and run their own companies, without any obvious distinction between the two. Now, users can see more details about each contact.

The app also has improved its algorithm for “Favorites,” a section of the app that shows who you contact the most in a colorful, tile-like photo format. Early on, some users said that the app wasn’t really showing them who their favorite contacts were; Brewster says it has now tweaked the app so that Favorites are truly top contacts. Favorites also shows your last method of communication with that person.

Brewster is the creation of New York-based entrepreneur Steve Greenwood, formerly of Facebook-acquired Drop.io. Greenwood says he had been formulating the idea for Brewster for five years before the product launched, using his extensive Excel spreadsheet (with more than 7,000 personal contacts and 30 category tabs) as a test case for the app.

It’s one of at least a few start-ups looking to tackle contact-management. My AllThingsD colleague Liz Gannes points out in her interview with Greenwood that apps like Xobni and Cue also offer “smart” address books. As consumers gather more and more contacts across multiple email and social networking accounts (far exceeding Dunbar’s number), some are turning to helpful utility apps like these to help them keep track of people.

But after the Path debacle last February, privacy is, naturally, of utmost importance to app users who are asked to give apps like Brewster access to accounts like Gmail, Facebook and Twitter upon signing up.

Brewster launched in July to a warm reception in the tech start-up world, but hit a small bump in the road early on. That same week, Brewster briefly exposed the contact information of some users, including actor and tech investor Ashton Kutcher. The company quickly fixed the bug.

Greenwood has insisted that users’ contact information should remain private, and that the company will not sell user data.

The New York City-based company behind the app had previously been under the radar, while hiring 15 people and attracting funding from top NYC venture capitalist Fred Wilson at Union Square Ventures.

It had a coming-out party today, with a story in the New York Times and a glowing write-up by Wilson.

The Brewster app merges various versions of contact info about each person in a user’s address book, from sources like Gmail, Facebook, Twitter, LinkedIn, Foursquare and the phone/address book. Brewster also delivers a feed of reasons to get in contact with people — birthdays, new jobs, and personal analytics that determine when people are falling out of touch.

And then the whole index is searchable, including not just names, but information drawn from Facebook, LinkedIn, Foursquare, email and more.

I was intrigued, and spent some time chatting with founder Steve Greenwood today about how Brewster might break through to become a personal utility. Here’s an edited transcript:

Liz Gannes: What’s the big goal of your start-up?

Steve Greenwood: This is a service about understanding the relationships in your life. Relationships are complicated, and more so over time, and w’re aiming to make that complexity of relationship awesome for you. To me, relationship complexity is the number of people we know, the number of contexts we know people through, and the number of ways we communicate with them.

I just got my personal analysis back from Brewster, and apparently there are 7,000 people I know.

The average broadly is like a thousand, so you are a super connector. If you think about it, if there’s 7,000 people you know, that’s a ton of relationships, a ton of history, a ton of inflection points. It’s a ton of metadata now for each person.

Explain to me when in the course of my daily life I will feel the need to use Brewster.

What we’re aiming to do is focus on who you know. It’s entirely private; it’s just for you. We hope to be the best complement and partner to the social Web. We don’t do any of our own messaging; we don’t do any connecting. The idea is, let’s make your experience even better on Facebook, on LinkedIn, on Twitter.

So, if Brewster is complementing other services, help me understand why you are a separate app that I need to use, rather than part of those platforms.

There’s a few core uses around Brewster. The first thing is having quick access to initiate communication with people you’re the closest to. Sometimes I’ll text you, sometimes call, sometimes Facebook, sometimes Twitter — but the thing is, it’s you.

The second thing is around the feed. So you’ll see social discovery within your own relationships — who’s trending in your life, who you should get in touch with, who you should get to know better. It should be an emotional moment when you see in your feed you’re losing touch with Suzie. Or you and I start communicating a lot, and you see, “Wow, Steve Greenwood’s trending in my life.” Or someone new just moved to your city, or even simple things like birthdays. All the things that come through the feed are what I call “inflection points.”

Brewster founder Steve Greenwood

So then I go to Brewster, I see something interesting about someone in my feed, and then click to their profile, and then choose a way to contact them and get launched into that other app?

Yeah. In that sense you could think of it like Google. We’re not focused on time on site; we want to be a great service that helps others do what they do.

I remember you had written a post on why can’t search and social get along, and this is like people search you’ve never seen before. So, for instance, I’m a big fan of the Knicks, I have tickets, and I could ask Brewster which of my friends should I take.

Does this replace my existing phone contacts app?

Yes. There’d be no reason to open up that; we will be as fast as native contact search, and there’s so much more to it.

Will Brewster archive all of my conversations with a certain person, or no?

Not today, and the reason is privacy. I wanted to make sure that we did right around security and privacy controls, and storing all these messages felt like a lot. If it turns out there’s tremendous value in it, we’ll do it.

It seems like you guys took an unusual move in allowing the general public en masse today, rather than metering access, and that’s impacting your performance. It took more than an hour for you guys to build my account, and your recommendations about who my favorite people would be were pretty off. Can you help set people’s expectations?

We had done tremendous load testing and performance testing before this, and the demand is well beyond what we’re expecting. In a clean environment, when we’re back to optimal levels, your account should take six minutes, and the average user should be under three minutes. We have one of the best engineering teams in New York, and a very ambitious project.

There was a lot of attention recently around various social apps retaining users’ contacts without making that clear. Obviously, you guys have to retain contacts, store them and keep them updated. How do you do it respectfully?

We’re pretty far from not just mentioning this — we put a whole page about it in the sign-up. First, part of the whole spirit around this is we’re solving our own problem, what would we want. And the second thing is the whole service is for you; it’s private, we will not sell user data.

But it’s not just my data, it’s an address book — so it’s all my contacts’ data, as well.

You and I have a relationship, and I have an understanding of that relationship. The physical world version of the address book is my mom’s version, where she had all the information and notes about each person, including some stuff that just my mom knew, and that’s what we’re trying to reflect here.

How do you plan to make money, and how are you going to introduce monetization in a way that doesn’t piss off existing users who are using your service for free?

This is a free service. The only focus we have right now is providing this cool beautiful app. Over time, there’s a lot of ways you could imagine we could make money. We’re never going to share your personal information with other parties, but the thing is that marketing in its purest form is actually wonderful, because it delivers things that are interesting to you.

Other people have also tried to put context around contacts; for instance, some of the better ones have been Xobni and Rapportive and the new Cue from Greplin. How are you different?

I think it’s an amazing time to be thinking about and working on this type of technology. This phase is really about personalizing technology and making it relevant to people. There’s a lot of great companies, including the ones you named. We have a very particular view of what we’re focused on, which is this idea of who you know, and it’s about creating a service that’s powerful, and something that’s really personalized — something that gets you, that understands you.

After a flurry of user confusion and uproar last week due to Facebook abruptly changing users’ default email settings to display @facebook addresses on individual profiles, Facebook once again faced public ire on Monday morning after many users discovered that primary email contacts in their cellphone address book were switched to display @facebook addresses. What’s more, many from both camps complained that they weren’t receiving some emails at all.

To combat the confusion, Facebook is trying to elucidate in plain English why we’re the ones doing it wrong, sending to members of the press detailed explanations on exactly how Facebook Messages is designed to work.

“If someone sends you an email to your @facebook.com email address and it’s from an address associated with a Facebook friend or friend of friend’s accounts, it will go into the inbox,” a Facebook spokeswoman told me in an email. “If it’s from an address not associated with a friend or friend of friend’s Facebook account, it will go into your other folder.”

That has been the main point of contention thus far: It was bad enough that Facebook planned an email switch-up, but now some users weren’t getting important emails at all.

“We’ve noticed that in a very limited number of cases, the bounce email back to the original sender may not be delivered because it may get intercepted by spam filters,” the spokeswoman said.

And after some mobile users began noticing their phone email contacts switching, things got downright ugly. Facebook swears this last part was a mistake, and expects to remedy it by tomorrow.

“For people on certain devices, a bug meant that the device was pulling the last email address added to the account rather than the primary email address, resulting in @facebook.com addresses being pulled,” the spokeswoman said. Those devices, we’ve seen, were primarily older Android phones. “We are in the process of fixing this issue and it will be resolved soon. After that, those specific devices should pull the correct addresses.”

Could Facebook have handled this any worse? Probably, though unless another unfortunately timed bug comes up in the near future, I expect it’ll all blow over by the end of the week.