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0

Untrusted TLS connection established to gmail-smtp-in.l.google.com I think you have a certificate chain error here. Make sure you are sending the intermediate certificate along with your certificate.


0

Based solely on the information given, examine your Content Filter configuration in Exchange Powershell: Get-ContentFilter | Format-List Specific attributes to look at: BypassedSenders ExternalMailEnabled Technet reference for Set-ContentFilter: https://technet.microsoft.com/en-us/library/aa996791(v=exchg.160).aspx


-1

@Stefan You seem very knowledgeable which is awesome, I looked over your headers, without your domain name it makes it very hard to help troubleshoot. The one thing I did notice in your headers is that you're using "Simple/Simple" to sign your DKIM, you should really switch that over to "Relaxed/Relaxed". A lot of mail servers have trouble with simple. ...


8

One thing missing in the above (excellent) replies is to set up outbound TLS. Gmail has started to punish senders not using TLS, and other providers aren't saying anything but I'm sure they will follow suit.


14

There should be no issues becoming a small mail provider. You seem to be doing the right things. Many large providers don't get things right, and hopefully get most of their mail delivered. If mail is being sent to the SPAM folder, it is likely you have missed something. There should be a record of why you have delivery issues: For bounced messages ...


3

Nowadays, the spam activities is a real headache. The Big guys like Gmail, Microsoft, Yahoo etc. trying to secure their users from the spams. Hence, they must improve their techniques to filter the spams. And due to the secure reason, they could not disclose their policies. Hence, we could not configure our servers which can communicate their servers. ...


1

You don't care what the MX record is compared to the rDNS record. You do care about the outgoing IP from your mailserver compared to the rDNS record for your domain. They may or may not be the same. So make sure that whatever address the email server is actually sending from has a corresponding reverse pointer that resolves to your email domain name. ...


3

These addresses aren't generated by the spammers, they are the result of bad address collection procedures. Spammers use various tools to find addresses to add to their send lists. Some of these tools will search through web sites, or emails sent to mailing lists, and snarf up anything that looks like an email address - which includes Message-ID:s. The ...


1

if emails are being sent by legitimate user/accounts, some of them might have fallen victims of malware that is using their email clients to send these messages, do you have any way to know their current OS/mail client? Logs may help you with that if you are not using SSL/TLS for your IMAP connections, IMAP credentials might have been captured through many ...


1

most likely you are open relay mail server, you can check here http://mxtoolbox.com/diagnostic.aspx open relay means that anyone can use you mail exchange unchallenged. you will need to look at the documentation around securing you mail server.



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