Server Management > Network Services > Email
The Email Server Settings allows the configuration of various email related functions on the BlueOnyx server. These services are divided between four sub-tabs:
BlueOnyx uses Sendmail as its SMTP agent and Dovecot for POP3/IMAP service. When the MTA is Postfix, SMTP on port 25 is handled by Postscreen whenever DNSBLs are enabled.
Turn the Simple Mail Transfer Protocol (SMTP) service on or off. Enabling SMTP will allow this server appliance to act as an SMTP server for sending and receiving Internet email between other servers. SMTP also allows users to use this server appliance for sending email.
Turn the SMTP over SSL service on or off. Important note regarding SSL
Turn SMTP authentication on or off. When off, SASL AUTH is not advertised on ports 25, 587 and 465.
Turn the Submission Port(587) on or off. Many network administrators and Internet Service Providers do not allow their users to connect with external SMTP servers using standard SMTP TCP port 25. BlueOnyx supports the use of Submission port on the standard TCP 587. Enabling this option will allow your users to connect on 587 as an alternative to 25.
Turn the Internet Message Access Protocol (IMAP) service on or off. Enabling this service allows users to retrieve email from this server appliance using email clients that support IMAP. IMAP allows users to store email on the server but requires continuous access to the server during the time users are working with their mail.
Turn the Internet Message Access Protocol over TLS/SSL (IMAPS) service on or off. Enabling this service allows users to retrieve email from this server appliance using email clients that support IMAPS. IMAPS allows users to store email on the server but requires continuous access to the server during the time users are working with their mail. Important note regarding SSL
Turn the Post Office Protocol (POP) mail retrieval service on or off. Enabling this service allows users to retrieve email from this server appliance using most standard email clients.
Turn the Post Office Protocol over TLS/SSL (POPS) mail retrieval service on or off. Enabling this service allows users to retrieve email from this server appliance using most standard email clients. Important note regarding SSL
Z-push is an open-source application to synchronize ActiveSync compatible PDAs and mobile phones, which allows them access to emails. For more information about how to use Z-Push see:http://www.blueonyx.it/index.php?page=z-push
Set how frequently this server appliance will deliver outgoing mail. Immediate delivery sends mail as quickly as possible but needs a full-time Internet connection. Periodic delivery is best for use with part-time Internet connections such as dial-on-demand.
Set the maximum size of email messages this server will send or receive. Please enter an integer greater than 0. The default value is to leave this field empty which will allow this server to send and receive email messages of any size.
Defines how many recipients the envelope of an email message may have. If emails have more recipients than specified here, then the email will be rejected.
delay_checks changes the order Sendmail checks if a connection is correct or not, this is a good option to us if you use RBL blacklists
Enter a domain name or IP address to override the From: address of email sent by users of this server. This feature is also called Domain Masquerade. Please enter a properly formatted IP address, host name, or domain name. The default value is to leave this field empty. For example, 192.168.1.100, www.example.com and example.com are valid entries.
Enter the fully-qualified domain name of an email server through which all outgoing email will be routed.
Check to enable SMTP relay trusts by POP authentication. If checked, any user who successfully uses POP to check mail will be trusted for 30 minutes to send email using the SMTP service. This feature is suitable for users who frequently travel.
Enter the IP addresses, host or domain names that are allowed to relay email through this server. A user will not be able to send outgoing email through this server unless the IP address, host or domain name of the machine they are connecting from is entered in this field. Please enter a list of IP addresses, host and domain names that will be trusted to relay email using this server. Networks may be specified by using 0's. For example, to allow relaying for a network 192.168.1.1 with subnet mask 255.255.0.0, specify the address 192.168.0.0.
Enter the host names and domain names that are not allowed to deliver email to this server. Please enter a properly formatted host name or domain name.The default value is to leave this field empty. For example, www.example.com and example.com are valid entries.
Enter the email addresses of users that are not allowed to deliver email to this server. Please enter a properly formatted email address. The default value is to leave this field empty. For example, user@example.com is a valid entry.
By default, BlueOnyx is activated with a self-signed SSL certificate. The use of SSL-enabled services (ie: POP3, IMAP, or SMTP) will likely result in certificate warnings from client devices. Users may configure their clients to accept and ignore the self-signed certificate warning. Alternatively, a signed SSL certificate may be installed on the server or an individual site.
Enter the domain name to which you want a secondary mail service.
Enter the main mail server for the domain.
DNS-based blacklists (DNSBLs) reject known spam sources at SMTP connect time. With Postfix, checks run in Postscreen on port 25. With Sendmail, the same GUI entries become FEATURE(dnsbl) lines. Weights and the DNSBL block threshold apply to Postfix/Postscreen only.
Add or edit a list with Blacklist service.
Postscreen rejects an incoming SMTP client when the sum of DNSBL weights for its IP is at least this number (1–99). The default is 1: one listing on any active list with weight 1 is enough to block.
Raise the threshold if you use several independent lists and only want to block when more than one list agrees (for example 2 or 3). A single list such as bl.spamcop.net with weight 1 and threshold 1 is a valid setup.
The table shows each configured DNSBL host, its Weight, and whether it is active. Use Add or Modify to open Blacklist service.
Typical public lists (always check the provider's terms; some require registration or a query key at higher volume):
bl.spamcop.netzen.spamhaus.orgb.barracudacentral.orgpsbl.surriel.combl.mailspike.net