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Exchange in house vs office 365 for security

Cobra25 asked
Last Modified: 2017-04-18
We are a highly secure organization dealing with high profile clients. Would you recommend we use exchange in house for email or is the cloud like office 365 safe and reliable?
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Senior Systems Engineer
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Wouldnt you rather have control of email in your hands though? Say this email account was for a celebrity.
Distinguished Expert 2019

The question comes down to exactly what the needs and requirements are. Cloud makes sense in some, but not all, cases. If you keep in house, you know that you have total control of the security, but on the other side of it, any security lapses/breaches are totally on you. What exactly have you agreed to in terms of response times, etc. (Food for thought...)

However, Elango has pointed out some good points about 365. If you decide to go that route, get a worthy spam filter service, not the Microsoft stuff.

Generally speaking, celebrities are going to care more that you're protecting properly them than how you're protecting them. Their legal folks of course are going to want more details.
Most Valuable Expert 2015
Distinguished Expert 2019

Depends on what you can offer them on-prem. For example adding a second-factor authentication in O365 is a three-click operation, while on-prem it will take significant investment. Encryption in transit and at rest is applied across the service and can be supplemented with IRM or S/MIME if needed. There are many other controls you can take advantage of in O365, of course some come at a price. Lots of compliance related stuff also.

Another point to make is that there are huge multi-national corporations using O365, Microsoft included. HPE, VMWare, Facebook, etc. Parts of the US government use O365 too, so one can make a case that it's secure enough for them. Which doesnt change the fact that you might be offering something else with your current offer, which is not found in the cloud.

Bottom line is, it always depends on the specifics.
Rich RumbleSecurity Samurai
Top Expert 2006

The counter points to hosted email is the same as it always was, and using the word "cloud" does not change the fact that its hosted :) 0365 does not guarantee you dedicated hosting/instances. Your email is on a sever or two with a few dozen others, technically. Your email is backed up to a tape/drive that contains dozens of other companies emails. Your exposure is the same as it ever was.
This is true even with the "single tenant" option. They do not spin up hardware just for that one tenant, you are on shared hardware. We had strict requirements if we were going to be hosted, and Microsoft finally relented and admitted to us that "single tenant" is "slightly more isolated" than multi-tenant. They would not expand, but did say too that backups could potentially contain the encrypted contents of other companies email, the encryption key would be the same across the whole backup tape.

We actually ended up using gmail. https://gsuite.google.com/learn-more/security/security-whitepaper/page-2.html
Not that google was anymore isolated, but that they talked openly and candidly about their security, and allowed us to work closely with them to develop our email service. Google's Spam filtering is top notch, and their virus protection has been better than Symantec and McAfee (we used both last year). Maybe it's because they own VirusTotal, I'm not sure, they wouldn't say :)
We've had 100% uptime, very responsive help and service, and a major reduction in spam.

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