SMTP relay with API key
would it be possible to provide an SMTP relay service using API keys so that E-Mails could be sent without the user's mailbox.org credentials? This would, for example, allow for easy automated E-Mails from routers, servers, password managers, etc.
So far I used my mailbox.org user credentials for sending automated E-Mails (status messages, critical allerts, etc.) via the mailbox.org SMTP server. However, depending on the application/system they might be stored as plain text in config files. I'd like to remove this potential security threat with API keys for just sending E-Mails, logging into the mailbox.org account with those keys would not be possible.
Currently I'm testing SendGrid, a provider of such an SMTP relay via API keys. Its API is simple and can be set up quite fast. Unfortunately most of their IP addresses for a free account are being blocked by mailbox.org (I'm receving the automated E-Mails with my mailbox.org account of course) as they are flagged by spamcop.net. I'm afraid that I'll have a similar issue with other providers.
Therefore my question whether such a service could be provided by mailbox.org. In order to avoid misuse, an hourly/daily/weekly/montly amout of E-Mails sent via such an API could be limited.