## How the mail is delivered?

When one sends mail with pine, elm, mh or some other User Agent it goes to the local postoffice program aka mailer like zmailer, smail, PP or sendmail which then tries to figure out using the domain part of the address to which postoffice this should be sent for delivery. When using Fully Qualified Domain Names (FQDN) they can be resolved using the hierachical Domain Name System to the IP address of the recipients postoffice where it will be delivered using the Simple Mail Transfer Protocol (SMTP). If the recipient isn't directly in the Internet the mail is usually delivered to a gateway mailer which lies in the border between two networks and can do the necessary conversions and relaying to the other network that uses for example NJE, DECNET or OSI protocols instead of Internet protocols or has some other reasons for using a gateway to Internet.

In many Unix hosts there's often a command mailq that shows the current queue of outgoing mail. Usually in the Internet the mail is sent to the destination within few minutes, but sometimes a network outage somewhere might cause the mail to be in the queue for few days for retrying untill it's finally sent back as undeliverable mail. If the mail gets to a remote postoffice you usually can just wait and hope it reaches it's recipient in time. Delays mostly occur to some remote places without good connections or due to major equipment failures. Also the recipient might not read the mail that often or don't have time to reply. Command finger user@mailhost.someplace.fi sometimes tells if the user has read his or her mail recently. Many places don't support that feature though.

Major problems in various networks are usually reported in some mailing lists or newsgroups like sfnet.tietoliikenne.katko or bit.listserv.linkfail but minor ones usually arent. If you have persistent problems you should contact your local postmaster(@your.domain).

In case you want to know more about User Agents read on. Otherwise you can return to the cover page.