Locating the Recipient
COPIAFACTS connects directly to the MTA for the recipient, determined by a DNS look-up for MX records. CopiaFacts uses the DNS settings specified in your Windows networking TCP/IP properties to find a name server to use. This server is queried to find the mail server for the destination address. If you have more than one DNS server address they are tried in turn until one is found which returns one or more domain names, normally provided in the sequence the remote MTA wishes them to be tried. You can control these retries with $email_settings.
If no MX or alias records are found, CopiaFacts strips elements (if more than two) from the domain name to find one which returns MX records. In this case CopiaFacts also places the addressee's own domain at the head of the list, so that it is tried first.
CopiaFacts then attempts an SMTP connection to each of the mail server domains in the list until the mail is successfully transmitted to the addressee or a local error is returned by the remote end (for example, mailbox full). This occurs before an error is returned and need not be taken into account when determining your retry strategy. The various possible errors are classified in the normal way (details in the Smart Retry SMR file) and may be retried if required, as specified by $email_retry_delays.