More companies than ever are considering e-mail as a service, but the options aren't easy to sort through.

Cost per user per month might seem like the overriding criterion, but adding options such as encryption can shoot up the price. Some vendors might not offer key features you need. That's why we created this buyer's guide.

Our requirements are that the service is provided to users via a Web browser, there's no hardware on the customer premises, and the service runs in a multitenant environment. Here's what we learned from the 10 vendors who responded to our buyer's guide questionnaire.

Price

SaaS e-mail gets in the door because it's cheaper. But you'll need to factor in a lot of add-on charges for most vendors to get an apples-to-apples comparison. Fully loaded, most business-class e-mail comes in at around USD 12 per user per month for a Microsoft Exchange service. Simple POP3 e-mail accounts will be a lot less, some only USD 1 per user per month.

When comparing SaaS ROI to on-premises, look at all of the hard on-premises costs, such as hardware, software licenses, staff support, and client licenses. Put a price on lost productivity from outages and any gain from shifting IT staff to more valuable initiatives. Some providers, such as Rackspace, also provide a client license such as Outlook or Entourage, so these costs also need to be considered.

Storage

From 1 GB to unlimited space, the vendors vary greatly in terms of how much storage they offer. This could be another big driver in the price, as some providers charge considerably for additional storage. E-mail archiving plays a big factor, too--the ability to archive e-mail and the pattern of storage your company requires will play a large role in the costs of the different providers. More qualitatively, look closely at how usable the search functions are and how quickly information can be retrieved from the archive.

Synchronizing To Smartphones

While all providers can do this synchronization, it's another cost driver and it can vary based on the smartphone you use, as well as the provider. Rackspace's syncing, for example, varies greatly by the service: USD 10 per user per month for BlackBerry (on top of the fees from your mobile provider), USD 3 for Active Sync, USD 15 for Good Mobile, and USD 19.95 for Apptix. We actually switched from BlackBerry to Windows Mobile because of the high cost of syncing fees--almost equal to the cost of the mailbox.

The value, however, can be tremendous. Keeping messages and calendar invitations synchronized across a highly mobile workforce is a key time saver for us, and it's crucial in some environments.

Exit Strategy

SaaS might not work out for you. Or the vendor might not deliver. So, as with any cloud service, before you get in you should know how you'll get out. For example, with the Google service, you can take your content with you and export all mail from Gmail (via POP or IMAP), or just forward your mail to any other service, at no cost.

In our environment, all e-mail is synchronized with desktops or laptops, which has several benefits. We had someone with a complete disk failure, and within 30 minutes, they had a new machine, connected to the shared e-mail service, and the mail replicated. Critical folders, including in-box, were there instantly, and the others took a few hours to sync almost 2 GB of data. For moving to another service, the configuration would work the same way: Each employee would be configured to connect and sync to the new service.

At the administrative level, we have seen problems with corporate-wide exports and imports. In addition to the sheer size of the data involved and folder structures, we see inconsistent results from the tools designed to help do this. Some will create a "Data" folder that places all folders in a single structure, and deconstructing this can be time consuming.

Conventional backup and restoration is another option, again at the individual user level. Recently, we eliminated our e-mail backup policies, relying on the SaaS provider's backup. This saves us bandwidth and time, as our backup provider is also in a cloud environment. Most of the providers offer full backups with redundant storage for all online mailboxes.

The Interface

User interfaces vary greatly. We use Outlook on the local machines and the Web client occasionally. While the Web interfaces can mirror much of the functionality within the local client, there may be minor differences, and some things seem faster in the native client.

The administrative interface is probably where you'll want to spend the most time. It's where you'll do all of your configuring of mailboxes and administer accounts, as well as monitor usage and billing. For companies that like to monitor or take control of employees' e-mail accounts, some services allow duplicate messages to inbound and outbound accounts, hidden from the user. It's potentially useful with terminated employees under difficult circumstances.

The activity can be logged for auditing of what administrators do with the account. Some features, unlike conventional premises-based e-mail servers, can't be disabled, so companies need to be aware of what they're getting.

Encryption And Security

All the vendors offer some level of encryption, most by partnering. Cost and type of encryption vary greatly, so be sure to spend a lot of time in this area if encryption is important to you. TLS tends to be included, whereas AES is usually an additional fee. The level of sophistication that vendors offer also varies greatly.

Explore how encryption is provided, and ensure that additional software isn't required on the client for those apps to work. Microsoft, for example, uses Voltage for encryption, providing a Web-based interface that means no added software on the desktop.

The other security area to consider is authentication. Generally, authenticating a SaaS e-mail application against Active Directory means your provider would need to integrate with your Active Directory; most don't. Without that, the SaaS provider maintains user names and passwords.

Most companies will be reluctant to give a SaaS provider integration access into Active Directory. Many won't do it, since caching and gaps in access to the domain controller may cause security and access problems. In terms of wide-scale enterprise adoption, the issues surrounding Active Directory are a big barrier for SaaS providers.

Overhead

Even when e-mail is delivered as an online service, there's still IT overhead associated with managing the accounts and any group or alias lists. In some cases, these are centrally located and internal IT teams can create different types of administrators, but they may not be exactly the type of profile you need. For example, it's impossible with some services to let someone create accounts but not delete them, or create aliases but not accounts. When it comes to SaaS e-mail, you'll have to adjust some of your policies to gain the benefits of the shared infrastructure.

Just be careful which compromises you make. I saw one organization that had about a dozen people as administrators of its SaaS e-mail, just so they could manage group and alias lists. From a security perspective, this isn't a good option.

However, as a user and administrator of SaaS e-mail, I can say the experience has been positive. The savings from the hardware, software, and maintenance burden far outweigh any cons. As providers incorporate more features, more companies will expand their SaaS footprints.