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SMTP relay

If your software can only send email over SMTP, point it at Flinkk Mail instead of changing code. The relay accepts the message, checks your API key, and sends it through the same system as the API, so suppression, limits, webhooks and logs all apply.

Settings

Setting	Value
Host	`smtp.flinkk.io`
Port, SSL/TLS	`2465`
Port, STARTTLS	`2587`
Username	`flinkk` (`apikey` also works, so SendGrid settings carry over)
Password	a Flinkk Mail API key for the domain you send from

Connections must be encrypted: the server only accepts a login after TLS starts. The From address must be on the domain the key was created for.

Examples

# Laravel .env
MAIL_MAILER=smtp
MAIL_HOST=smtp.flinkk.io
MAIL_PORT=2587
MAIL_USERNAME=flinkk
MAIL_PASSWORD=your_api_key
MAIL_ENCRYPTION=tls

import smtplib
from email.message import EmailMessage

msg = EmailMessage()
msg["From"], msg["To"], msg["Subject"] = "hello@yourdomain.com", "customer@example.com", "Welcome"
msg.set_content("Glad you are here.")
with smtplib.SMTP("smtp.flinkk.io", 2587) as s:
    s.starttls()
    s.login("flinkk", "your_api_key")
    s.send_message(msg)

For WordPress plugins such as WP Mail SMTP, choose "Other SMTP", host smtp.flinkk.io, encryption SSL, port 2465, authentication on, username flinkk and your API key as the password. For Node.js see Nodemailer.

What is supported

Text, HTML or both, unicode subjects and bodies, attachments (up to 10), Cc, Bcc and Reply-To.
Custom headers X-*, List-Unsubscribe, List-Unsubscribe-Post, List-Id, Precedence and Auto-Submitted.
Up to 50 recipients each in To, Cc and Bcc, and messages up to about 3 MB including attachments.
A retry of the same message (same Message-ID) is recognised and not sent twice.

Not supported: inline images referenced by cid: (they arrive as attachments), and calendar parts. Use the API for those.

Replies from the server

Reply	Meaning
`250`	Accepted; the text ends with the email id you can look up in the logs.
`535`	Wrong username or API key.
`550`	Permanent: the address is suppressed, or the key cannot send from that domain.
`552` / `554`	Permanent: message too large, too many attachments, or no body.
`451`	Temporary: a rate or daily limit, or a service problem. Mail software retries these automatically.
`454`	Too many failed logins from your address; try again in ten minutes.

On this page: Settings · Examples · What is supported · Replies from the server