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In general, it's fine to have an individual email account @gmail/hotmail/yahoo/etc. - even if someone's using it for their "work" address (enough people switch jobs frequently enough to want to have something "portable" for maintaining professional connections). However, when you're trying to say "this is my business'es email address", it just looks shady to not have a @business.TLD address. By itself, use of a web mail service provider, such as Google, Microsoft or the like isn't necessarily cause for stigma (specifically "distrust"). However, given how cheap it is to get a domain name, and how cheap and easy it is to get that domain hosted by a webmai provider such Google, Microsoft or the like, it looks amaturish: if the company can't be bothered to spend a couple bucks a year for just a domain and a Google Apps (et. al.) account, what else can't they be bothered to do?