How exactly works sending e-mails from SharePoint?

Question

I have basic information about alerts, I can setup them, manage them via CA or power-shell scripts, I can test the SMTP sending functionality via telnet if they are not sent, but still don't know how exactly they works.

Do you know about some web address or manual with detailed information please?

I'm looking for answers like:

• Notification (subscribe) e-mails are sending directly from WFE? How?
• Alerts via owstimer? How?
• Is there any queue for undeliverable alerts?
• If they are sending from all three servers in farm, can we direct them to one server only? (because we can catch undeliverable ones when alerts stop working).

Alerts are very important for some our application and when job fails, we lost a lot of notifications in a black hole...

Answer 1

There is a lot of very useful information from Microsoft but SharePoint Alerts are counter-intuitive on a lot of levels. The number one rule when dealing with them is to never assume that they follow a predictable pattern because they do not and will surprise you every time. They also love to work perfectly for 100 days straight, then for no discernible reason, they will break in some creative way for a day or three, then will work perfectly again, all with no intervention. If you delve into custom alerts then it only gets worse.

The linked article sheds a lot of light on them but here are some quick highlights

• Alert subscriptions are stored in the content database associated with the alert, not anywhere in the user profile
• Alerts emails are sent via the timer service
• The timer service checks for new alerts to send every 5 minutes
• Alert emails are not generated when an event happens that would trigger the alert. Instead, the timer job compares the alert subscriptions to tables in the content database and then builds the email at that time.