go-mail

Email in a Go module.

Include the module and easily integrate an email client or a server with closures (callbacks).

* SMTP Client and Server {RFC 5321} (with {RFC 8314} and without TLS)
* ESTMP Extensions (8BITMIME, AUTH, STARTTLS, ENHANCEDSTATUSCODE, PIPELINING, SMTPUTF8)
* DKIM {RFC 6376}

* POP3 {RFC 1939} (with {RFC 8314} TLS)
* IMAP4 {RFC 3501} (INCOMPLETE, WIP, BETA)

Functions

SendMail()
	SMTP Client that supports DKIM, ESMTP AUTH and STARTTLS.

SmtpServer()
	Start SMTP Server(s) with or without TLS, there are closures for each step of the SMTP process.

Pop3Server()
	Start POP3 Server with TLS, there are closures for each step of the POP3 process.

Imap4Server()
	Start IMAP4 Server with TLS, there are closures for each step of the IMAP4 process.

ParseTags()
	Parse string with key=value tags to map[string]string.

Examples

Read the examples in examples/.

Installation

cd go/src
git clone github.com/andrewhodel/go-ip-ac
git clone github.com/andrewhodel/go-mail

SendMail() and TLS

If outbound_mail.RequireTLS is true, TLS or STARTTLS must be used on the connection.

Absolutely secure outbound Email via SMTP with TLS

Set outbound_mail.RequireServerNameOfReceivingAddresses = true or any router in the network path between the SMTP origin and the SMTP destination can steal or copy the email being sent.

The routers between the mail servers can steal emails by acting as the destination IP address. Although verification of origin is achieved by DKIM, the destination server is only verified if the origin server requires the TLS servernname of the destination server and validates that it is the same as the destination domain in the email address.

That means that email hosting as provided by Google Workspaces (looks like Gmail) for domains other than gmail.com will fail to receive email with outbound_mail.RequireServerNameOfReceivingAddresses = true if Google Workspaces does not require their customers to upload a TLS certificate and the destination domain of the email address does not match that of the server.

SendMail() returns a TLSInfo string of each server connected to that tells the TLS ServerName, Hostname and IP Address. The Hostname and ServerName can be proven to match.

License

MIT

Verification of Authorship

The OP_RETURN data in this BTC transaction provides a sha256 checksum of the project file. The BTC transaction provides a transaction date. The file contains the author and the work.

https://blockstream.info/tx/0914c23220712ff2eb96b4c49b7c2df3a128be04a5abd67ed3831d680a70c4a4?expand

mail.go

    commit                  3fade57d4b48c4910e39be46036e6bea3629ec73
    sha256                  f74ef27f51929dce6aa70d6519addf87ff7a642980fe62dad5c2e738ae6ad137
    op_return               7368613235362066373465663237663531393239646365366161373064363531396164646638376666376136343239383066653632646164356332653733386165366164313337
    bitcoin transaction     0914c23220712ff2eb96b4c49b7c2df3a128be04a5abd67ed3831d680a70c4a4
    date                    4/9/2024