smtp From

[vodish]

Standart headers

MAIL FROM:<ivan@example.com>
RCPT TO:<recipient@example.com>
DATA
From: Ivan Petrov <ivan@example.com>
To: Recipient Name <recipient@example.com>
Subject: Test
Date: Sun, 12 Apr 2026 10:00:00 +0000

Hello!
.

in the standard library, the headers "MAIL FROM:" and "From:" are not separated. This leads to an error

mail := smtp.Mail{
  from:      'Ivan Petrov <ivan@example.com>' // ERROR
  to:        'recipient@example.com'
  subject:   'Test'
}

client.send(mail) or { panic(err) }

V panic: Sending mailfrom failed
 v hash: e3a161e
    pid: 0x9476
    tid: 0x9476
/tmp/v_0/tsession_7e4601c59740_01KP0F6JT4BB7XRBF1R99ZN8Y3/email1_test.01KP0F6JTKCHD7H5HX77628TVB.tm:16705: at builtin___v_panic: Backtrace
/tmp/v_0/tsession_7e4601c59740_01KP0F6JT4BB7XRBF1R99ZN8Y3/email1_test.01KP0F6JTKCHD7H5HX77628TVB.tm:38840: by main__send_email
/tmp/v_0/tsession_7e4601c59740_01KP0F6JT4BB7XRBF1R99ZN8Y3/email1_test.01KP0F6JTKCHD7H5HX77628TVB.tm:38526: by main__test_send_email
/tmp/v_0/tsession_7e4601c59740_01KP0F6JT4BB7XRBF1R99ZN8Y3/email1_test.01KP0F6JTKCHD7H5HX77628TVB.tm:41426: by main

v/vlib/net/smtp/smtp.v

Line 110 in 6e32bd9

pub fn (mut c Client) send(config Mail) ! {

v/vlib/net/smtp/smtp.v

Line 245 in 6e32bd9

sb.write_string('From: ${cfg.from}\r\n')

[swilcox]

You've hit a real bug in vlib/net/smtp/smtp.v. The Mail.from field is being used for two different things that have different syntax rules:

• SMTP envelope (MAIL FROM:) — per RFC 5321 must be a bare mailbox, e.g. <ivan@example.com>. No display name.
• Message header (From:) — per RFC 5322 may include a display name, e.g. Ivan Petrov <ivan@example.com>.

In send_mailfrom:

c.send_str('MAIL FROM: <${from}>\r\n')!

If from = 'Ivan Petrov <ivan@example.com>' this emits

MAIL FROM: <Ivan Petrov <ivan@example.com>>

which is malformed, so the server rejects it and you get the Sending mailfrom failed panic. The same shape exists in send_mailto for RCPT TO:.

In message_data the From: header is written verbatim from cfg.from, so display-name form is fine there.

Workaround today

Pass only the bare address:

mail := smtp.Mail{
    from:    'ivan@example.com'
    to:      'recipient@example.com'
    subject: 'Test'
}

Trade-off: no display name in the From: header.

Proposed fix

Opened #27072 which adds a small envelope_addr helper to extract the bare mailbox for the envelope commands while leaving message_data (and therefore the From: / To: headers) untouched — so from: 'Ivan Petrov <ivan@example.com>' will work end-to-end: the envelope gets <ivan@example.com> and the header stays From: Ivan Petrov <ivan@example.com>.

Feedback on the approach welcome — an alternative would be to add an explicit envelope_from / sender field on Mail instead of parsing, but that's a bigger API change.

[JalonSolov]

#27072 has been merged. In future, please create issues, rather than discussions, when reporting a bug. Issues can be auto-closed when PRs are merged, while discussions must be handled manually.