If you connect to the internet via a dialup connection, or for some other reason don’t have permanent internet connection, sending mail will fail when you are not connected. The SMTP library implements queued delivery, and the following variable control its behavior.
smtpmail-queue-mail ¶The variable smtpmail-queue-mail controls whether a simple
off line mail sender is active. This variable is a boolean, and
defaults to nil (disabled). If this is non-nil, mail is
not sent immediately but rather queued in the directory
smtpmail-queue-dir and can be later sent manually by invoking
smtpmail-send-queued-mail (typically when you connect to the
internet).
smtpmail-store-queue-variables ¶Normally the queue will be dispatched with the values of the
SMTP variables that are in effect when M-x
smtpmail-send-queued-mail is executed, but if
smtpmail-store-queue-variables is non-nil, the values
for smtpmail-smtp-server (etc.) will be stored when the mail is
queued, and then used when actually sending the mail. This can be
useful if you have a complex outgoing mail setup.
smtpmail-queue-dir ¶The variable smtpmail-queue-dir specifies the name of the
directory to hold queued messages. It defaults to
~/Mail/queued-mail/.
The function smtpmail-send-queued-mail can be used to send
any queued mail when smtpmail-queue-mail is enabled. It is
typically invoked interactively with M-x
smtpmail-send-queued-mail RET when you are connected to the internet.