Brev

A cli that send email directly to the mx servers of the world

Install

go get github.com/modfin/brev/cmd/brev
go get github.com/modfin/brev/cmd/brevd

Brevd Usage

The Brevd is server for transactional emails via http api.

Configure

• Choose a host domain you are going to use for the brevd server, eg. brev.cc
• Choose a client domain from which to send emails, eg. example.com
• Find out what ip you are running the service on, eg 1.2.3.4
• Generate a dkim key-pair, eg brev gen-dkim-keys --key-size=2048. This generates two files. dkim-private.pem is loaded into brevd and dkim-pub.dns.txt which is put into a TXT record on the client domain

Host DNS Config

Add a A record for your server, eg mx0.brev.cc pointing to the ip, 1.2.3.4
Should result in the following

dig A mx0.brev.cc

;; ANSWER SECTION:
mx0.brev.cc.            260     IN      A       1.2.3.4

Add a MX record for your server to for your domain, eg brev.cc pointing to the brevd server
Should result in the following

dig MX brev.cc
 
;; ANSWER SECTION:
brev.cc.                300     IN      MX      10 mx0.brev.cc.

Add a SPF policy through TXT record for your domain, eg brev.cc pointing to you brevd server, eg v=spf1 mx -all
Should result in the following

dig TXT brev.cc 
brev.cc.                300     IN      TXT     "v=spf1 mx -all"

Finally, set up PTR records through your ISP, eg 1.2.3.4 -> mx0.brev.cc

Client DNS Config

Say you now want send your emails and have them come from no-reply@example.com

Add a SPF policy to example.com through TXT record pointing to the brev.cc domain, eg v=spf1 include:brev.cc -all
Should result in the following

dig TXT example.com
 
;; ANSWER SECTION:
example.com.              60      IN      TXT     "v=spf1 include:brev.cc -all"

Add a DKIM public key to example.com by choosing a selector, eg brev and adding the public key to TXT record at brev._domainkey.example.com
Should result in the following

dig TXT brev._domainkey.example.com

;; ANSWER SECTION:
brev._domainkey.example.com. 300  IN      TXT     "v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8A....;"

Server config

Create a run script that configures the environment for you

cat ./run-brevd.sh
export BREV_HOSTNAME=mx0.brev.cc
export BREV_DB_URI=$(pwd)/brev.sqlite

export BREV_MX_DOMAIN=brev.cc
export BREV_MX_PORT=25

export BREV_DKIM_SELECTOR=brev
export BREV_DKIM_PRIVATE_KEY=./path/to/dkim-private.pem
brevd

Brev Usage

The Brev cli is a small utility to send emails directly to a MX server

NAME:
   brev - a cli that send email directly to the mx servers

USAGE:
   brev [global options] command [command options] [arguments...]

COMMANDS:
   help, h  Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --subject value     Set subject line
   --from value        Set from email
   --message-id value  set the message id
   --to value          Set to email
   --cc value          Set cc email
   --bcc value         Set cc email
   --text value        text content of the mail
   --html value        html content of the mail
   --attach value      path to file attachment
   --help, -h          show help (default: false)

Example

brev --subject="An attachment" \
        --to="someone@example.com" \
        --cc="someone-else@example.com" \
        --cc="someone-compleatly-different@example.com" \
        --attach="/path/to/a.file" \
        --text='The body of the email'