IMail Processing Order
Incoming mail addressed to a valid local address is processed in the following order.
- The SMTPD service checks if the connecting IP is listed in the Access Control dialog box. If it is listed in deny access list, the connection is denied. If it is listed in the grant access list, the connection is allowed and processing continues.
- The SMTP service checks if the e-mail address listed in the "Mail FROM" address command to see if it is listed in the Kill List.. If the address or domain present, the SMTP service returns an error to the connecting client and does not accept the message. If no match is found, the SMTP service accepts the message.
- . If enabled, fights unwanted mail at the perimeter, reducing incoming messages at the entry-point, before these messages enter the network.
- . If you have DomainKeys / DKIM verification enabled, you can control incoming e-mail identified as spam by signature errors.
- . If you have Realtime Blacklists enabled, IMail compares the connecting IP address to the blacklists to determine if a match occurs. If a match occurs, the e-mail may be deleted (depending on the Realtime Blacklist configuration) or an X-Header may be added and processing continues.
- If you have the verification tests enabled, they verify the "Mail FROM" address, the HELO/EHLO domain, and perform a reverse DNS lookup. If any of these checks fail, the e-mail may be deleted (depending on the configuration) or an X-Header may be added and processing continues.
- If you have the SPF feature enabled, it provides increased capability to stop incoming e-mail from forged e-mail addresses. Using a sender authentication scheme, a domain owner requires that legitimate messages from a domain must meet certain SPF criteria. Messages that do not meet the criteria are not accepted as a legitimate e-mail message and are processed according to the SPF options selected on the SPF tab.
- If you have IMail Anti-virus installed, it checks the message for infected files or code. If infected, the mail is repaired, bounced, redirected, or deleted, according to the settings on the tab. If the file is not infected, content filtering attempts to identify whether the message is spam .
- If you have the optional Premium Anti-spam filter installed, it provides automated spam protection in addition to the Standard Anti-spam filter included in IMail. Premium Anti-spam filter settings are applied before Standard Anti-spam filter settings.
- If you have content filtering enabled, it determines if the message is likely to be spam. If the message is determined to be spam, it is either deleted, sent to the specified address, or an X-Header is inserted. If the message is not spam, aliases are checked.
- IMail Server checks to see if the addressee matches an alias in the destination domain. An alias is considered to be any of the following: standard alias, group alias, program alias, or a list-server mailing list name.
- If there is a match to a program, IMail Server executes the program.
- If there is a match to a standard or group alias, IMail Server resolves the alias to the appropriate user ID(s), and checks the user ID.
- If there is a match to a list-server mailing list name, IMail Server (a) processes the mail according to the settings for that list, and (b) checks the user IDs specified in the list settings.
- If no match to any alias, IMail Server checks the user ID.
- IMail Server determines if the user ID is valid for the destination domain. If invalid, the mail is returned to the sender. If valid, the delivery rules for a list-server mailing list are checked.
- If the message matches the rule criteria for a list, delivery follows according to the rule. If not, then the message is sent to the list server. If the message is not addressed to a list, is checked.
- IMail Server determines if the message matches a rule for the mail host. If so, delivery follows according to that rule. If not, then rules for the user ID are checked.
- IMail Server determines if the message matches rule criteria for the user ID. If the message matches rule criteria for a user ID, then delivery follows according to the rule. If not, then is checked.
- IMail Server determines whether an address is present in the box on the General tab for this account. If so, IMail Server forwards the mail. If not, the mail is delivered to the user ID according to the established delivery rules.
- IMail Server determines whether the user ID has the Info Manager enabled. If so, the automatic response is sent and the message is delivered to either the forwarding address or (if no forwarding address) to the sub-area or mailbox specified. If the Info Manager is not enabled for this user ID, the vacation setting is checked as described in the next step.
- IMail Server determines whether the user ID has a vacation message enabled. If so, the vacation message is sent. If not, the message is delivered to the User ID.