For example, something that is too complex for your comfort level, a security concern, or maybe your hardware can’t keep up with the service’s needs?
For example, something that is too complex for your comfort level, a security concern, or maybe your hardware can’t keep up with the service’s needs?
Standing up email might not be that hard… but it’s much harder to ensure that your mail will actually be delivered successfully. Plus it’s not a service you can typically afford to go down. Any emails you miss during that downtime are gone forever, whereas even if my Vaultwarden credential vault goes down I can access passwords from a device that has things cached at least while I fix things.
Plus the big providers just treat small mail servers with a lot more skepticism than they did 20 years ago.
The sending server will retry a few times, so you have at least a few days to bring it back. And if you prefer an additional fail-safe - adding a secondary MX somewhere else which will just store mails until the primary comes back is trivial.