Applications are the lifeblood of any modern business, whether they are for email, CRM, or various other tools that are utilized in day-to-day business life. Since these tools are so vital, many companies look to place them in infrastructure that is always available with no downtime, so that employees can perform the tasks they need to so that they can be productive. Since availability is one of the biggest benefits the cloud can provide, companies are looking to moving these applications to the cloud, though it isn't always the best move available.
Just like any other application, you need to know what the requirements are before you move it anywhere - after all, installing a Windows copy of Microsoft Office on a Mac won’t get you very far, and similar concepts apply to the cloud. If you are moving an application that is very sensitive (anything that has regulations in place to protect it, for example), that is probably not the best fit for the cloud - not because the application won’t work, but because of the multi-tenant nature of the cloud, which might be a violation to a regulatory agency involved with your field. Looking at programs that may genuinely have issues in the cloud, a good example might be older applications that are unable to utilize multiple cores of processing power - these applications simply won’t be able to take advantage of the technology in the cloud, and may actually run slower than they would outside a cloud environment.
Applications that DO take advantage of the cloud well are applications that can benefits from one of the key benefits of the cloud - scalability. So email applications, PBX, conferencing and collaboration tools all work very well in cloud environments. After all, today you might only need 100 users for your email application, and tomorrow you might need 1,000 - this kind of growth can be taken care with some simple adjustments to the cloud, as opposed to large scale investments that traditional IT infrastructure would need.
Availability is another big advantage to the cloud - it is available anywhere that you have an internet connection, regardless of whether it comes from your phone or the office. So if you are a heavy user of applications that are used on the go - CRM and storage applications, for example - then you have some great candidates for applications to move to the cloud. If you have a mobile sales team that needs to access customer records and contracts, it is a great benefit for them to be able to simply tap at their phone to produce the documents they need, so they can focus on closing the sale as opposed to hunting down a printer to create the documents they need. These two types of applications also benefit from scalability - as your sales force grows, your ability to expand the resources the application can utilize can grow as well. 
Alejandro
