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| server:mail [2018/10/29 15:13] – [Tags] Details on the FidoNet netmail gating and cleaned up the tags section digital man | server:mail [2020/07/01 14:58] – grasshopper |
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| download and delete those messages (which could potentially include | download and delete those messages (which could potentially include |
| false positives). | false positives). |
| | |
| | ===== sbbs.ini ===== |
| | |
| | The ''[mail]'' section of the ''[[dir:ctrl]]/[[config:sbbs.ini]]'' file supports the following configuration settings (''key = value'' lines): |
| | |
| | ^ Key ^ Default Value ^ Description ^ |
| | | Interface | [global] Interface | Comma-separated list of IPv4 and IPv6 network interfaces to listen on for incoming SMTP/SMTPS connections | |
| | | POP3Interface | [global] Interface | Comma-separated list of IPv4 and IPv6 network interfaces to listen on for incoming POP3/POP3S connections | |
| | | OutboundInterface | 0.0.0.0 | IPv4 network interface to use for outgoing SMTP/SMTPS connections (0.0.0.0 = //any interface//) | |
| | | SMTPPort | 25 | TCP port number to listen on for incoming SMTP mail-delivery connections | |
| | | SubmissionPort | 587 | TCP port number to listen on for incoming SMTP mail-submission connections | |
| | | TLSSubmissionPort | 465 | TCP port number to listen on for incoming SMTPS (encrypted) mail-submission connections | |
| | | POP3Port | 110 | TCP port number to listen on for incoming POP3 mail-retrieval connections | |
| | | TLSPOP3Port | 995 | TCP port number to listen on for incoming POP3S (encrypted) mail-retrieval connections | |
| | | MaxClients | 10 | Maximum number of simultaneous incoming TCP sessions supported | |
| | | MaxInactivity | 120 | Maximum amount of TCP session inactivity before timeout and disconnection (in seconds) | |
| | | MaxDeliveryAttempts | 50 | Maximum number of outbound mail delivery attempts before mail is bounced back to sender | |
| | | RescanFrequency | 60M | Frequency (in seconds) of mail base re-scans for outbound mail to be sent/re-sent | |
| | | SemFileCheckFrequency | 2 | Frequency (in seconds) of checks for semaphore files | |
| | | LinesPerYield | 10 | Interval (in message body lines) of thread-yields during message receive (0 = none) | |
| | | MaxRecipients | 100 | Maximum number of mail recipients for a single inbound SMTP mail message | |
| | | MaxMsgSize | 20MB | Maximum size of incoming SMTP mail messages, in bytes | |
| | | MaxMsgsWaiting | 100 | Maximum number of messages allowed in a (non-W-exempt) user's inbox | |
| | | ConnectTimeout | 30 | Timeout (in seconds) before blocked outbound SMTP/TCP connections are aborted | |
| | | HostName | [global] HostName | Hostname of this server | |
| | | TempDirectory | [global] TempDirectory | Directory to use for the storage of temporary files | |
| | | RelayServer | | Hostname or IP address of SMTP server to relay outbound mail through (requires ''RELAY_TX'' option) | |
| | | RelayPort | 25 | TCP port number to connect with when relaying mail to RelayServer | |
| | | RelayUsername | | Username used to authenticate with RelayServer | |
| | | RelayPassword | | Password used to authenticate with RelayServer | |
| | | DNSServer | <auto> | IP address of DNS server used to discover mail-exchange servers for outbound mail destinations | |
| | | DefaultUser | | Default recipient of mail for unrecognized recipient names (blank = none) | |
| | | DefaultCharset | | Default MIME Content-Type ''charset'' value when unspecified (e.g. ''IBM437'') | |
| | | DNSBlacklistHeader | X-DNSBL | Header value to add to incoming mail messages from DNS-Blacklisted servers | |
| | | DNSBlacklistSubject | SPAM | Word to insert into beginning of subject of mail messages from DNS-Blacklisted servers | |
| | | POP3Sound | | WAV file to play upon incoming POP3 connections (Windows only) | |
| | | InboundSound | | WAV file to play upon incoming SMTP/SMTPS connections (Windows only) | |
| | | OutboundSound | | WAV file to play upon outgoing SMTP/SMTPS connections (Windows only) | |
| | | NewMailNotice | "New e-mail from <%s>\r\n" | Format of telegram to send users upon receipt of incoming mail message | |
| | | ForwardNotice | "and it was forwarded to: %s | Additional telegram text to send to recipient of automatically forwarded mail | |
| | | JavaScript* | [global] JavaScript* | JavaScript-related settings for external mail processing | |
| | | LogLevel | [global] LogLevel* | Minimum severity of log messages to be displayed / stored | |
| | | BindRetryCount | [global] BindRetryCount | Maximum number of TCP port bind attempts before failure | |
| | | BindRetryDelay | [global] BindRetryDelay | Delay (in seconds) between TCP port bind retries | |
| | | LoginAttempt* | [global] LoginAttempt* | Failed login attempt throttling / filtering / banning | |
| | | Options | ''ALLOW_POP3'' | Mail server option flags (see below for details) | |
| | |
| | ==== Options ==== |
| | |
| | The ''Options'' key of the ''[mail]'' section of the ''[[dir:ctrl]]/[[config:sbbs.ini]]'' file supports the following option flags (separated by a ''|'' character): |
| | |
| | ^ Option ^ Description ^ |
| | | USE_SUBMISSION_PORT | Support mail submissions on the SMTP submission port | |
| | | TLS_SUBMISSION | Support incoming SMTP Submissions (encrypted) connections | |
| | | ALLOW_POP3 | Support incoming POP3 connections for BBS users to use mail clients to retrieve the mail in their BBS inbox | |
| | | DEBUG_POP3 | Log all POP3 activity (Debug log level) | |
| | | TLS_POP3 | Support incoming POP3S (POP3/TLS) connections | |
| | | DEBUG_TX | Log all transmissions (Debug log level) | |
| | | DEBUG_RX_HEADER | Log headers of all received messages (Debug log level)| |
| | | DEBUG_RX_BODY | Log body text of all received messages (Debug log level)| |
| | | DEBUG_RX_RSP | Log all received responses (Debug log level) | |
| | | ALLOW_RX_BY_NUMBER | Allow email to be received by user number in addition to name/alias (not recommended) | |
| | | ALLOW_SYSOP_ALIASES | Allow email to received for various administrative aliases (e.g. "sysop", "postmaster") to be delivered to the sysop | |
| | | NO_NOTIFY | Do not send telegrams to users notifying them of newly received email | |
| | | NO_HOST_LOOKUP | Do not resolve/log hostnames of incoming TCP connections | |
| | | USE_TCP_DNS | Use TCP instead of UDP for MX-record queries using DNS | |
| | | NO_SENDMAIL | Do not send outbound Internet email | |
| | | ALLOW_RELAY | Allow authenticated users to relay Internet email through this server | |
| | | SMTP_AUTH_VIA_IP | Authenticate users via IP address when supported | |
| | | DNSBL_REFUSE | Actively refuse all mail sessions from DNS-blacklisted servers | |
| | | DNSBL_IGNORE | Ignore (silently-discard) mail from DNS-blacklisted servers | |
| | | DNSBL_BADUSER | Block (report "invalid mailbox") mail from DNS-blacklisted servers | |
| | | DNSBL_CHKRECVHDRS | Check "Received" headers in mail messages for DNS-blacklisted servers | |
| | | DNSBL_THROTTLE | Throttle mail sessions from DNS-blacklisted servers | |
| | | DNSBL_SPAMHASH | Store hashes of confirmed SPAM messages for later comparison | |
| | | SEND_INTRANSIT | Send mail that is marked 'in-transit' (not recommended) | |
| | | RELAY_TX | Relay outbound SMTP mail through an intermediary SMTP RelayServer | |
| | | RELAY_AUTH_PLAIN | When relaying mail to a RelayServer, use SMTP-PLAIN AUTH | |
| | | RELAY_AUTH_LOGIN | When relaying mail to a RelayServer, use SMTP-LOGIN AUTH | |
| | | RELAY_AUTH_CRAM_MD5 | When relaying mail to a RelayServer, use SMTP-CRAM_MD5 AUTH | |
| | | NO_AUTO_EXEMPT | Do not automatically exempt outbound mail recipients in ''dnsbl_exempt.cfg'' | |
| | | NO_RECYCLE | Do not allow this server to be automatically recycled by external event | |
| | | KILL_READ_SPAM | Mark received SPAM messages for "Kill after read" | |
| | | MUTE | Disable all sound (WAV) files from playing | |
| | |
| | ===== Email Security ===== |
| | |
| | In order to prevent one's emails from being labeled as SPAM, or worse, rejected. More and more Servers are starting to reject email that is not being secured to prove that it has come from a reliable source and not some spammer. This page will walk through the steps of securing your email server. |
| | |
| | //Note: This page assumes one owns a domain name and that domain name is the name to be used for one's BBS. If one uses synchro.net for emailing purposes, this will not apply in that case.// |
| | |
| | ==== Dynamic IP Address - No problem ==== |
| | - Find a Dynamic Domain Server (DDNS) provider |
| | - There are many out there. There are even some free ones that will give at least one address which is all that is needed |
| | - This provider should provide directions on this initial setup |
| | - Setup an "A" record with whatever name is appropriate |
| | - This name won't be visible and serves as just a target for one's owned domain name to point to |
| | - Next step is to setup records on the owned Domain Name |
| | |
| | ==== Domain Name Records Setup ==== |
| | - Log into one's provider of the domain name |
| | - Create an "A" record for the owned domain name |
| | - Create a "CNAME" record with the host name as one's BBS name or something else if prefered (i.e. this will be the address of one's BBS) |
| | - This should point to the address created in the DDNS provider |
| | - Create another "CNAME" record with the host name as 'mail' or some name that signifies it will be the name of the SMTP address |
| | - This should also point to the address created in the DDNS provider |
| | - Create a "MX" record and the host name should be the "@" symbol |
| | - This should point to the 'CNAME' in step 4 |
| | - Next is to setup the "TXT" records that make the email being served more secure |
| | |
| | ==== Creating the 'TXT' records for security ==== |
| | - Still logged into one's provider of the owned domain name, create a "TXT" record (i.e. This will be the SPF record) |
| | - The host name should be the "@" symbol |
| | - The TXT Value will contain the information that will state which domain names and IPs are OK if email comes from one of those. One will want to include all possible Domain Name/IP addresses that could serve up email. This part takes a little more effort to get the text right. Thankfully there are free tools available on the internet that will generate the SPF text for you. These are a couple of those sites. |
| | - https://www.spfwizard.net/ |
| | - https://www.dmarcanalyzer.com/spf/spf-record-generator/ (shows how to create an SPF record manually) |
| | - Create another "TXT" record (i.e. This will be the DMARC record) |
| | - The host name for this record has to be _dmarc |
| | - The value specifies where to send reports of abuse of one's domain name. |
| | - There is an online tool to help with the creation of the value of this record: |
| | - https://dmarcian.com/dmarc-record-wizard/ (there could be other's, this was just the first one I found) |
| | - Create yet another "TXT" record (this is the final one and it is the DKIM record) |
| | - This record will allow for the verification of the signage on the email that is placed by the MTA((Mail Transport Agent)) using a private key and the DKIM record has the public key. Thus emails can be verified against the DNS record. |
| | - **Note:** DKIM capabilities is currently __not__ available in Synchronet. |
| | - None-the-less, having the other records should help alleviate emails from being marked as junk/spam mail. |
| | |
| | === Validation Check === |
| | * There are a couple of sites that can help with validating that the records are setup correctly: |
| | * https://mxtoolbox.com/MXLookup.aspx (Click the 'MX Lookup' button, then click the 'Find Problems' button) |
| | * https://www.dmarcanalyzer.com/spf/checker/ (under tools menu one can select dmarc also) |
| | * Check for any errors and correct them. If most every check turns up 'Green', then the records should be correct. |
| | * //Note: If your SPF record doesn't have an Domain Name/IP address that is used in delivering the email, the email will still be flagged as junk/spam// |
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| ===== See Also ===== | ===== See Also ===== |
