15 votes
Accepted

How do I get off Mimecast's greylist?

They recommend to keep retrying and eventually the IP should get greylisted. We've configured our Postfix to do this. All bounced emails get retried a few times but Mimecast is not removing us off ...
MadHatter's user avatar
  • 80.4k
6 votes
Accepted

How to set up mx records

The problem seems to be that you have other servers than your mail server listed in your MX record, one of which has a lower priority. MX records work on a lowest-priority-first basis, which means ...
MadHatter's user avatar
  • 80.4k
6 votes

Is it a DMARC failure if disposition=none & dkim=fail?

Your current DMARC policy is v=DMARC1; p=none; rua=mailto:[email protected]; ruf=mailto:[email protected]; pct=100; The p=none; means you are asking the receiver to take no action ...
Esa Jokinen's user avatar
  • 49.5k
6 votes
Accepted

Gmail does not accept mail from a new VPS server with PTR setup

Your PTR record for IPv6 is setup correctly (and strictly speaking it seems to be no longer required by Gmail). Saying that one hint is in the message Gmail sends to you: or the corresponding forward ...
Tomek's user avatar
  • 3,553
5 votes

Email Spoofing Or Something More Sinister?

I'm with Ruscal on this. If you send an email to Jane and you recieve this bounceback then it's clearly because a forward has been set up on Jane's email account, either intentionally or maliciously.
joeqwerty's user avatar
  • 111k
4 votes

Avoid Mail Delivery System Bounce Forward

My recommendation is to change the envelope sender on the auto-reply sent at step (2) of your flow. It is this envelope sender address, which will receive any error messages at step (3). You can use ...
kasperd's user avatar
  • 30.7k
4 votes

Restrict users to send emails only from a particular IP address to reduce SPAM

This is done by implementing different security solutions: SPF: text DNS record for your zone that specifies what server is allowed to send from your domain; this is not restricting but major email ...
Julie Pelletier's user avatar
4 votes

after changing nameserver email not coming, Got domain from godaddy, site hosted on hostgator and gmail service from Google suite

If you delegate nameservers then the full setup belongs to the delegated nameservers (hostgator in your setup) and they will need to setup MX records for you. As, from your description it looks like ...
Federico Galli's user avatar
4 votes
Accepted

Why are emails sent to me bouncing with incorrect MX records error message?

You have a CNAME record on your @ as well as MX, and very likely SOA and NS records. This is NOT ALLOWED by DNS standards, specifically RFC1912, Section 2.4: 2.4 CNAME records A CNAME record ...
Tomek's user avatar
  • 3,553
4 votes
Accepted

Not able to send mail using postfix-sendmail and getting bounced

The message: Feb 19 04:36:59 server postfix/smtp[26045]: 732DD106D41: to=<[email protected]>, relay=in.hes.trendmicro.com[54.219.191.21]:25, delay=1.5, delays=0/0/1.3/0.21, dsn=5.7.1, ...
Anderson Medeiros Gomes's user avatar
3 votes
Accepted

How to set postfix to just ignore mail to nonexistent users

I don't see mynetworks = specified in your Postfix configuration main.cf. If this is not specified, then anyone on the same local network as you can relay mail through your server without ...
Michael Hampton's user avatar
3 votes
Accepted

550 Verification failed Sender verify failed (in reply to RCPT TO command)

You have a really strange setup telnet mail.abcgreenbrier.org 25 Trying 63.142.252.80... Connected to mail.abcgreenbrier.org. Escape character is '^]'. 220 mn-vps-01.cbcmcalester.com ESMTP Postfix (...
ALex_hha's user avatar
  • 7,283
3 votes

554 5.7.1 unknown recipitent

The problem here is that the recipient mail server is blatantly lying. It's sent an SMTP error code 554 5.7.1 that means it is refusing to relay mail, but in the human readable text, it states "...
Michael Hampton's user avatar
3 votes

Is it possible to change MX records without downtime/returning/dropping messages?

If you change the TTL value of your MX records well in advance I don't think your stale records will live on for 72 hours after the switchover. Next if your old mail server is down, it won't accept ...
Tommiie's user avatar
  • 5,667
3 votes
Accepted

Message-ID of delivery report is equal to original mail

I just checked one of my bounced emails and the original sent email. Original message has a Message-ID header with a value similar to this: Message-ID: <XYZ@mydomain> Bounced message refers ...
OldSkoolDev's user avatar
3 votes
Accepted

Reverse DNS PTR record

A PTR record contains the hostname corresponding to the given IP address. Therefore you enter in your fully qualified domain name. You must also append a dot to it, though your provider's control ...
Michael Hampton's user avatar
3 votes

Postfix: How to check if my email headers are RFC5321/RFC5322 compliant?

The boilerplate referring to fixing your mail syntax is not likely indicating a problem with that specifically - it is just one of the things you can do while there may not be much you can do about e....
anx's user avatar
  • 9,649
3 votes
Accepted

Mail Bounce due to Invalid string MX record

The destination domain has a malformed MX record. $ dig mx smart.com.ph ; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.amzn2.4 <<>> mx smart.com.ph ;; global options: +cmd ;; Got ...
flowerysong's user avatar
3 votes

How to avoid emails sent to Google's deep web crawler

Inspecting IP address of the requests with reverse DNS, all three requests come from cache.google.com. When doing a reverse lookup, do not forget to check if a forward lookup of the host name points ...
Bob's user avatar
  • 31
2 votes

Postfix sent mails are bounced or go to spam

Gmail gives your explanation why mail was classified as spam. Did you check that? If each of your domains has dedicated IP, you need to check that its A and PTR records are in sync. This increases ...
user1700494's user avatar
  • 1,662
2 votes

Anyone have a Powershell script to look up the MX record for a domain?

On Server 2012/Windows 8 and above you can use Resolve-DnsName: Resolve-DnsName -Name mydomain.com -Type MX Source Use PowerShell to Quickly Check Multiple MX Records.
Chris Magnuson's user avatar
2 votes

Email bounce notification for an email account that doesn’t exist in exim mail server

As noted in the comment to your question, the Exim Documentation covers address validation. Bouncing particular addresses can be done easily by adding an alias to /etc/aliases. This is usually the ...
BillThor's user avatar
  • 27.9k
2 votes
Accepted

How to properly setup DNS for subdomain used only for sending

450 The error-message from the remote SMTP-server is most likely because they are verifying that there is an MX or A record for the domain given in the MAIL FROM: <> SMTP command. If your From-...
tlund's user avatar
  • 241
2 votes
Accepted

Email address tagging doesn't work with virtual mailboxes in postfix

In /etc/postfix/master.cf configuration file, ensure that the definition of dovecot service, referenced by virtual_transport configuration parameter, is set to suppress the extension part of the ...
Anderson Medeiros Gomes's user avatar
2 votes
Accepted

Postfix before-queue spam reject with amavis without sending out a bounce on OS X Server

The problem here is that it's amavis, not postfix, that's rejecting the message. Here's the standard flow for incoming messages: postfix receives the message from the sending MTA (or spambot) postfix ...
Gordon Davisson's user avatar
2 votes
Accepted

email backscatter returns not seen on mail server

The bounce messages should contain Received headers that show at least some of the servers the message passed through. Email headers are a valuable resource in investigating issues like this. The ...
BillThor's user avatar
  • 27.9k
2 votes

Configure server to ignore NDRs to forged addresses/domains

In short, to prevent backscatter you configure your mailserver to reject an undesired e-mail message during the SMTP transaction, rather than accepting the message first and then rejecting it at a ...
HBruijn's user avatar
  • 80k
2 votes

Disable the sending of "Undeliverable Mail Returned to Sender" in Postfix

Found the answer here. How do I configure Postfix to never send NDR responses? For example, if someone tries to send an email to a user that doesn't exist, I don't want my server to respond and ...
bistromath's user avatar
2 votes
Accepted

Postfix 451 4.3.5 Server configuration error

Search /etc/postfix/filtered_domains for ACCEPT on the right-hand side. You probably meant these to be OK, as described in Postfix documentation (man 5 access). Then postmap /etc/postfix/...
Cedric Knight's user avatar
2 votes
Accepted

Remove AS that's falsely associated with our IP from email block list

There is a misunderstanding. AS does mean Anti Spam, it's a rule number and not an Autonomous System Number. So you are just running in an ordinary spam protection rule at outlook.
sebix's user avatar
  • 4,373

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