Zig

Send DKIM Signed Email

See more DKIM / DomainKey Examples

Demonstrates how to send DKIM signed email. Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    const mailman = try chilkat.MailMan.init();
    defer mailman.deinit();
    const dkim = try chilkat.Dkim.init();
    defer dkim.deinit();

    // SMTP server settings...
    mailman.setSmtpHost("SMTP_DOMAIN");
    mailman.setSmtpUsername("SMTP_LOGIN");
    mailman.setSmtpPassword("SMTP_PASSWORD");
    mailman.setSmtpPort(465);
    mailman.setSmtpSsl(true);

    const email = try chilkat.Email.init();
    defer email.deinit();

    email.setSubject("This is a test");
    email.setBody("This is a test");
    email.setFrom("Chilkat Support <support@chilkatsoft.com>");

    // Add some recipients (BCC recipients are added below)
    email.addTo("Chilkat Software", "chilkat_software@yahoo.com") catch {};
    email.addTo("Chilkat Admin", "admin@chilkatsoft.com") catch {};
    email.addCC("Chilkat Admin", "admin@chilkat.io") catch {};

    // When sending an email with a DKIM signature, the MIME
    // of the email must not be modified prior to
    // or during the sending process.  Therefore, the MIME of the
    // email is assembled, the DKIM signature is added, and then
    // SendMimeBd is called to send the email.

    // First get the MIME of the email.  Calling RenderToMimeBd
    // causes the email to be signed and/or encrypted if those options
    // have been selected.  The MIME returned by RenderToMimeBd
    // is the exact MIME that would've been sent if SendEmail was
    // called.  We'll add a DKIM signature header to this MIME and then send...
    const bd_mime = try chilkat.BinData.init();
    defer bd_mime.deinit();
    mailman.renderToMimeBd(email, bd_mime) catch {
        std.debug.print("{s}\n", .{try mailman.getLastErrorText(alloc)});
        return;
    };

    // To create a DKIM signature,
    // you'll need to provide the following:
    // (1) An RSA private key in any common file format.
    // (2) The domain name (typically the same domain
    // as the sender of an email).
    // (3) A selector for the domain name -- an arbitrary string
    // to identify the matching public key in DNS.

    // To allow an email recipient to verify the DKIM signature via an
    // external email client supporting DKIM or using other software,
    // you will need to create a DNS record with the selector
    // and matching public key.  This example does not provide
    // information about DKIM DNS record creation.
    // (Chilkat does not provide an API for creating DNS records.
    // Creating the DKIM DNS record is something you would do
    // manually.)

    // Set the domain and selector:
    // You'll need to provide your own values here..
    dkim.setDkimDomain("chilkatsoft.com");
    dkim.setDkimSelector("brisbane");

    // Load a private key from any common RSA private key
    // format, such as DER, PKCS8, PEM, XML, etc.
    // The LoadDkimPkFile method automatically detects
    // the file format and reads it appropriately.
    // If a password is not required, you'll still need to provide
    // an empty password string argument, but it is ignored.
    const password = "passwd";
    const priv_key = try chilkat.PrivateKey.init();
    defer priv_key.deinit();
    priv_key.loadAnyFormatFile("qa_data/pem/rsa_passwd.pem", password) catch {
        std.debug.print("{s}\n", .{try priv_key.getLastErrorText(alloc)});
        return;
    };

    dkim.setDkimPrivateKey(priv_key) catch {
        std.debug.print("{s}\n", .{try dkim.getLastErrorText(alloc)});
        return;
    };

    // Add the DKIM-Signature header to the MIME in bdMime
    dkim.dkimSign(bd_mime) catch {
        std.debug.print("{s}\n", .{try dkim.getLastErrorText(alloc)});
        return;
    };

    // If desired, examine the MIME of the email being sent.
    bd_mime.writeFile("qa_output/dkimSigned.eml") catch {};

    // ---- Prepare to send the email contained in bdMime ---

    // To send to multiple email addresses, the strRecipients should be set to a comma-separated
    // list of email addresses.

    // Note: This is where we can add additional BCC addreses.
    // Here we are adding "chilkat.support@gmail.com" as an additional BCC address.
    // Notice that the 1st three email addresses are NOT BCC because these email addresses
    // appear in the MIME header of the email (in the "To" and "CC" header fields).
    // A BCC email address does not appear in the MIME, and thus the non-BCC recipients cannot see
    // that the email was also sent to the BCC address.  (BCC means "blind carbon copy")
    const str_recipients = "chilkat_software@yahoo.com, admin@chilkatsoft.com, admin@chilkat.io, chilkat.support@gmail.com";
    const str_from = "support@chilkatsoft.com";

    mailman.sendMimeBd(str_from, str_recipients, bd_mime) catch {
        std.debug.print("{s}\n", .{try mailman.getLastErrorText(alloc)});
        return;
    };

    mailman.closeSmtpConnection() catch {
        std.debug.print("Connection to SMTP server not closed cleanly.\n", .{});
    };

    std.debug.print("DKIM Signed Mail Sent!\n", .{});
}