Outsourced messaging services
Outsourced messaging services use a cloud computing paradigm of a third party providing the service. If the third party provides the end user interface, the model is Software as a Service, but when the offering is defined as application-to-application, such as a mail server, the vendor provides Platform as a Service.
Messaging services are inherently distributed, and now extend to service beyond email, such as short message services such as texting, and pager services. When sent in a corporate context, for example, instant messaging services may be less formal to the user than email, but still need to be archived for possible litigation or law enforcement discovery. Outsourced services that are commercially available meet different sets of customer needs for the same basic messaging functions.
Messaging service providers (MSP) list some of the reasons for outsourcing, although it must be remembered that this is marketing. For example, some say they will not have configuration errors, but no in-house or outsourced service is perfect. What is true is that an provider that has full-time configuration specialists is less likely to have an error than a small business with a part-time administrator, but the comparison is more difficult for a large enterprise that maintains a skilled in-house staff. The MSP decision is most often based on economy of scale, although it also may consider capital expense (CAPEX) and operating expense(OPEX), especially when having to meet new regulatory requirements.
- In-house unexpected failures: these are unplanned outages due to errors and disasters
- Data loss windows: depending on the system, there may be a shutdown while a backup is taken, or a backup may not capture the most recent messages; MSPs say they are protected against this because they have multiple levels of offsite service. An enterprise, however, can have multilevel storage, perhaps with a mixture of archives and caches. Multilevel backup may be too complex for a small business.
- Staffing costs
- Need to rearchitect at various levels of scaling or component life
- Optimal copies (i.e., deduplication)
- Validating that archives are tamperproof
- Rearchitecting due to operational or legal changes in data retention requirements
- Unpredictable deployments
- Too much local customization with support knowledge in a few minds
- Limited capabilities of Microsoft Exchange Server
There are a variety of good reasons to outsource messaging security functions such as screening for malware and spam, although such outsourcing must fit the enterprise trust and accountability model. Often, different appliances or services are involved with the malware and spam functions, although they may still come from the same MSP. Examples include:
- Barracuda networks, a mixture of onsite appliances and outsourced services
- Barracuda Spam and Virus Firewall 
- Dell EMS Email Security, an outsourced service
- Google Postini, an outsourced service
- White paper: Solving On-Premise Email Management Services with On-Demand Services, Dell Modular Services, 2009
- Barracuda Products Overview, Barracuda Networks
- Barracuda Spam and Virus Firewall, Barracuda Networks
- Hosted security and archiving services for your business, Google Postini
- Protect your business with web virus and spyware protection, Google Postini
- Protect and secure your existing email system, Google Postini