What This Field-Set Is For

 The System Emails field-set says how this Yioop sends the mail it sends of its own accord: the message activating a new account, the link inviting somebody to witness a secret ballot, a notification, a bulk mailing. It has nothing to do with the mail accounts people read and write here, which the Mail Services field-set below covers.

 These settings live on Server Activity rather than beside account registration, because mail is sent for more reasons than registering.

Use Built-in SMTP Client

 Checked, Yioop sends the mail itself, with the client built into it, and none of the fields naming somebody else's mail server are needed or shown. Where this machine runs a mail server of its own, that is, where Mail Services below is set to MailSite or to MailSite and External Mail Accounts, the message is handed to it and that server carries it the rest of the way. Where this machine runs no mail server, Yioop carries the message to each recipient's own mail server itself, so a site with mail services turned off can still send.

 Carrying a message that way needs a way out of this network. The ordinary mail port is tried first and the submission port after it, since many networks will not let mail out on the first. Which port a recipient's server took is written down, so only the first message to a domain waits out a port that will not answer.

 Unchecked, Yioop sends through somebody else's mail server, and the fields naming it appear:

SMTP Server

The host name of that server.

Server Port

The port to reach it on.

Mail Username

The account to sign in as.

Mail Password

That account's password.

Mail Security

How the connection is protected, such as STARTTLS.

Use a Queue

 Checked, a message is written into a folder and sent by the Media Updater on its next round rather than during the web request that asked for it. This keeps a page from waiting on a slow mail server, at the cost of the message going out a little later, and it needs the Media Updater to be running: with it stopped, a queued message waits where it is.

 Unchecked, the message is handed over during the request. A page that tells somebody an email is on its way, such as the invitation to witness a ballot, is the case this suits.

Sender Email

 The address the mail is sent from, such as bot@yourdomain. Where this Yioop runs its own mail server, the address has to be at a domain this site is set to receive mail for, and its local part must not be a name somebody already holds an account under.

When Nothing Arrives

 The mail log, under the work directory, holds a line for every message with what the far server said. A message that was never handed over says so there, and names the port and the answer that came back, which is usually enough to tell a stopped mail server from a network that will not let mail out from a name the far side refused.