| 37 | 37 | * Permanent failures, for which no retry will succeed. These include "no such user". In traditional email processing (read, sendmail), these failures get bounced right away. It doesn't serve any purpose to keep processing permanent failures as retries. Some we might deal with automatically, but if not, we do want to keep them around for the site admin to deal with. We could move these to a holding queue. |
| 38 | 38 | * Temporary failures, for which a retry may be succeed at some point. These include mailer misconfiguration or outage, no response from destination host, "user mailbox full"... Traditional email processing will eventually bounce even temporary failures. (If we want different retry rates for messages that have repeatedly failed (or, say, for different urgency levels), we could use separate queues with separate periodic tasks. Messages could be demoted into less frequent queues based on number of retry failures.) |
| | 39 | |
| | 40 | Speaking of traditional email processing, one option is to hand off sends to a standard external mailer, like postfix. Advantages are: |
| | 41 | * We wouldn't be reinventing the wheel. |
| | 42 | * Postfix has excellent email handling. |
| | 43 | * Dominic points out that it may be possible to use postfix for other transports besides email. |
| | 44 | Disadvantages: |
| | 45 | * If we can't use postfix for all the other transports, we'd still have to keep send queuing in Eden. |
| | 46 | * We wouldn't get direct feedback from send attempts. Getting error info would allow warning users if their sends aren't going through within the context of msg, which is where they sent from. It would also allow alerting the site admin to config and operational problems. If postfix (or other external mailer) has an API, we might be able to get errors that way. Or we might scrape errors from its log. That might be more trouble than doing the queuing inside Eden. |
| | 47 | * Postfix doesn't run under Windows (appears to be a broad consensus on this) -- it would need to be run on Linux in a virtual machine. There are mailers for Windows (at least for Windows Server) but they'd need different configuration. |
