When we look at the requirements we see the following. An online email service requires an online connection which might not always be given, either because of the location of the user or a problem with it. It might also be that the email service itself is down and not offering services. All those cases would mean that it would be impossible to read or send emails.

A local client does not have these restrictions as it stores all emails locally which ensures access even without Internet connection. It requires on the other hand that one (or the few) computer(s) to work with.

I think it’s pretty much a matter of personal taste. I prefer to have my data close to me, as silly as it may sound. If something unforeseen happens I can still access my data providing I took care of creating backups and stuff like that.

Security is another aspect that might be worth investigating. Many email service providers like Yahoo or Google use the email accounts for various services on other parts of their sites. Google users can use Google Analytics, Adsense, Adwords, Google Talk and several other services all with that one account. This increases the chance of loosing the account due to an attack. Could be phishing, could be an exploit that makes use of the fact that you can be still logged into your Google account even if you closed the mail application. Just look at the top right of a Google search form. Do you see your email address listed there? If yes you are still logged in. Attackers have way more possibilities to attack the online accounts than local ones.

It’s on the other hand very convenient to use online accounts. Being able to log in from anywhere is a huge selling point. The question is if this feature is needed by many users. I for one use only my main computer and my laptop to check emails. If the need would arise for an online account I would still want to have all my mail on my own computer even if I would use an online service from time to time.

Which leads to the question: What about you? Are you using email clients or online email services? Let me know.