The difference between the needs of Mailinator ("Email can reside in RAM because it is temporary (3-4 hours)") and most corporate e-mail services are... large. If you treat e-mail as ephemeral, sure, you can run on a single box somewhere, and in the case of a failure, a stateless recovery will have the service up and running again.
Meanwhile, if you're a business, you have actual compliance requirements on how long you have to keep an e-mail around.[1] SarbOx says you have to keep documents related to insider dealings _indefinitely_. Do you, the sysadmin, know which e-mails those are?
So you need backups. If you aren't testing your backups, you might as well not have backups. So you need a second server sometimes to test backup restores on. Do you deal with HIPAA protected information? If so, now you have a bunch of compliance requirements about the security of those e-mails and those backups you just made.[2]
It turns out that "you can save hundreds of dollars a month on e-mail by introducing an existential risk to your business in the event of a lawsuit" is not a great value proposition for most businesses, and most businesses are better off just going with Office 365 or Google Apps for Business, which have dedicated compliance officers and certifications for all of these issues and a lot that I haven't named.[3][4]
Yes, it is possible to overarchitecture things. Yes, there are CIOs and CTOs who want to cargo cult their way to success by imitating successful cloud migrations done by others. But there are a lot of real business problems out there that can be solved by doing things differently than they were done 10 or 20 years ago.
Meanwhile, if you're a business, you have actual compliance requirements on how long you have to keep an e-mail around.[1] SarbOx says you have to keep documents related to insider dealings _indefinitely_. Do you, the sysadmin, know which e-mails those are?
So you need backups. If you aren't testing your backups, you might as well not have backups. So you need a second server sometimes to test backup restores on. Do you deal with HIPAA protected information? If so, now you have a bunch of compliance requirements about the security of those e-mails and those backups you just made.[2]
It turns out that "you can save hundreds of dollars a month on e-mail by introducing an existential risk to your business in the event of a lawsuit" is not a great value proposition for most businesses, and most businesses are better off just going with Office 365 or Google Apps for Business, which have dedicated compliance officers and certifications for all of these issues and a lot that I haven't named.[3][4]
Yes, it is possible to overarchitecture things. Yes, there are CIOs and CTOs who want to cargo cult their way to success by imitating successful cloud migrations done by others. But there are a lot of real business problems out there that can be solved by doing things differently than they were done 10 or 20 years ago.
1) https://www.intradyn.com/email-retention-laws/ 2) https://www.hipaaguide.net/hipaa-email-compliance-requiremen... 3) https://docs.microsoft.com/en-us/office365/servicedescriptio... 4) https://support.google.com/googlecloud/answer/6056694?hl=en