Can SMTP retries come from different IP addresses?
Novox asked: I have a FortiMail with Greylisting turned on. The idea is that only after a valid SMTP retry, an email will get released. However, it appears that for …
Exim4 : "Connection timed out" whatever the forwarding smtp server
AJN asked: Exim is configured on a newly provisioned VM from a public cloud provider with public IPs (scaleway.net) Purpose: Be able to send mails from CLI (or scripts) to …
Postfix bounce when unable to validate TLS option
Nico asked: I’m using postfix as mail transfer agent on my mailgateway to send and receive emails. Because I’m communicating with sensitive information I’m using the tls options to validate …
Email server with no smtp connection
Terry asked: Ubuntu 18.04 on Google Compute Dovecot + postfix I figure I should be able to connect to a port other than 465/587, and since I can relay all …
Do I have to, and how do I setup bounce emails HELO command?
Skippy le Grand Gourou asked: Our server has been listed several times on CBL (see this question) because it “attempted to send email without using the HELO/EHLO command”. Grep’ing on …
Postfix transport map always using catchall definition
user203913 asked: Hoping one of the Postfix experts on here can help me debug an issue I am having with transport maps. I’ve gone through a the recommend list of …
Which side of this SMTP conversation is correct?
Mike B asked: I have an odd scenario with two mail servers communicating with one another and need help determining which one is behaving correctly. It’s a little complicated to …
Detect spammers on my server
mfuesslin asked: I recently got one Undelivered Mail Returned to Sender while sending my newsletter to one of my 1500 customers. My website uses a double-opt-in procedure to make sure, …
How to configure Postfix to send specific error code for a domain?
Henno asked: I need to configure Postfix to send 451 4.7.0 Temporary problem, please try again later for a specific domain. I have tried to google for returning custom error …
What's the point of repeating an email address in "The Envelope" and the "The Header"?
TLDR asked: I learned that both the FROM address and the TO address is repeated in a hidden element called the “envelope”, and then repeated again in the “body”. Question …