Some SMTP servers have special requirements. The following variables implement support for common requirements.
smtpmail-retries ¶An SMTP server may return an error code saying that there’s a transient error (a ‘4xx’ code). In that case, smtpmail will try to resend the message automatically, and the number of times it tries before giving up is determined by this variable, which defaults to 10.
smtpmail-local-domain ¶The variable smtpmail-local-domain controls the hostname sent
in the first EHLO or HELO command sent to the server.
It should be set only if the system-name function returns a
name that isn’t accepted by the server. Do not set this variable
unless your server complains.
smtpmail-sendto-domain ¶The variable smtpmail-sendto-domain makes the SMTP library
add ‘@’ and the specified value to recipients specified in the
message when they are sent using the RCPT TO command. Some
configurations of sendmail requires this behavior. Don’t bother to
set this unless you have get an error like:
Sending failed; SMTP protocol error
when sending mail, and the debug buffer (see Debugging)) contains an error such as:
RCPT TO: someone
501 someone: recipient address must contain a domain