Service/smtp

Hostnames

hostname	service	port	function
smtp.sugarlabs.org	smtp	25	Local delivery (plain SMTP)
smtp.sugarlabs.org	submission	587	SMTP with STARTTLS, legacy
smtp.sugarlabs.org	submissions	465	Email relay (SMTP with SSL, password authentication required)

Hosted on

Machine/sunjammer

Administrative contact

• postmaster AT sugarlabs DOT org

Sysadmins

• Bernie Innocenti
• (add yourself here if you tend to the postmaster RT queue)

Notes

• Users with a Sugar Labs shell account on sunjammer can use our SMTP relay for personal email submission. Any abuse will be prosecuted.

• The submissions port (465) is preferred for email relay. Unauthenticated and unencrypted connections are not allowed to relay.

• All email originating from the sugarlabs.org domain must be submitted through our SMTP server. Failure to do so may result in your email being blocked by spam filters.

SPF

Our domains use a non-strict (~all) SPF records.

You can add an spf record in the zone file in the form

 hostname         TXT     "v=spf1 redirect=_spf.hostname.sugarlabs.org"
 _spf.hostname    TXT     "v=spf1 ip4:IPv4_of_hostname/mask ip6:IPv6_of_hostname/mask a:hostname.sugarlabs.org mx:hostname.sugarlabs.org ~all"

The a and mx values are authorized mail server by domain name and authorized server by domain MX record, the MX record should also be defined for hostname.

Also maintain spacing and formatting for each section you add in the zone file.

DKIM

Our domain publishes a DKIM key.

To test DKIM, send an email to autorespond+dkim@dk.elandsys.com

To generate an ed25519 key to use for DKIM, you can use openssl

 # Generate ed25519 key
 $ openssl genpkey -algorithm ed25519 -out dkim_private.pem
 # Generate public key from private key
 $ openssl pkey -in dkim_private.pem -pubout -out dkim_public.pem

For ed25519 keys, the p value in the DKIM record must only contain the BASE64 encoded public key, without an ASN.1 structure

 $ openssl asn1parse -in dkim_public.pem -offset 12 -noout -out /dev/stdout | openssl base64
 VGhpcyBpcyBqc3V0ZSBhc29ka2ZvYXNrZWpkZmtsc2pkZgo=

Your entry would look like this

 selector1._domainkey.hostname      TXT     "v=DKIM1; g=*; k=ed25519; p=VGhpcyBpcyBqc3V0ZSBhc29ka2ZvYXNrZWpkZmtsc2pkZgo="
 _adsp._domainkey.hostname          TXT     "dkim=unknown"

When using an ed25519 key, you'll need to add a fallback RSA key for backward compatibility.

 # Generate rsa key
 $ openssl genrsa -out rsa_private.key 2048
 # Generate public key from private key
 $ openssl rsa -in rsa_private.key -pubout -outform der 2>/dev/null | openssl base64 -A

You can then add a KeyTable and SigningTable to your opendkim.conf

 KeyTable                refile:/etc/opendkim/KeyTable
 SigningTable            refile:/etc/opendkim/SigningTable

 # Contents of KeyTable with both keys
 selector1._domainkey.hostname.domain-name hostname.domain-name:selector1:/path/to/selector1/private/*.key
 selector2._domainkey.hostname.domain-name hostname.domain-name:selector2:/path/to/selector2/private/*.key

 # Contents of SigningTable
 *@hostname.domain-name selector1._domainkey.hostname.domain-name
 *@hostname.domain-name selector2._domainkey.hostname.domain-name

Then add a DKIM record for the second selector

 w-mail._domainkey.weblate       IN      TXT     ("v=DKIM1; h=sha256; k=rsa; p="*")

The value of p is the public key of the generated RSA key above.

Ensure your private keys are on hostname.

See also

• Service/imap
• Service/webmail
• Service/email