email sending issues to GoDaddy account

[chind]

Hi,
I'm running my own email server on virtualmin and using an account on here to send voicemail to emails from the fusionpbx. This is working for every customer apart from one. They have an email hosted by GoDaddy and use microsoft 365 as their client. They never receive an email from the FusionPBX. If I send an email using the same account but from a FreePBX, the client receives the email. If I send an email from the webmail portal, the client receives it. It just seems to be the way in which FusionPBX sends emails, but I can't find a specific parameter that would be causing this. Just wondering if anyone else has had an issue like this and how, or if, you got it resolved.

Thanks for your time and I look forward to hearing from you.

 

[Adrian Fretwell]

The big providers are making it increasingly difficult for people running their own email servers. Some are not following IETF guidelines and are ignoring the RFCs on the basis that "they know better". Just make sure that when you send emails from an authorised account on your mail server, they are DKIM signed and you have the correct SPF records in place on your DNS server.

 

[chind]

Hi Adrian,
Thanks for taking the time to reply. I have set the DKIM and SPF and when I send a message from the fusionpbx to mail-tester.com I get a score of 8.6/10 so I'm pretty happy with that. It just definitely seems to be something to do with the fusionpbx, because the freepbx will send an email using the same email account and the client will receive it. I'm trying to migrate my customers off freepbx onto fusion but now it seems I might have to re fire up the freepbx. Uurrrghh.

 

[Adrian Fretwell]

You may need to look at email headers in detail, and compare the working ones with the non working ones. As I said, some providers are doing non industry standard things like silently dropping emails (No non delivery response/reason) that they don't like to look of. For example, I have seen messages silently dropped if the Date header is missing. I have also seen messages dropped if the Message-ID header is missing. I ended up using a bit of Python to create it:

import smtplib
from email.message import EmailMessage
import email.utils as utils

#<snip>
    m = EmailMessage()
    m['Subject'] = sub
    m['From'] = self.smtp_from
    m['To'] = rps
    m['Date'] = utils.formatdate(localtime=True)
    m['Message-ID'] = utils.make_msgid(domain=settings.SMTP_DOMAIN)
#</snip>

 

[mcs3ss2]

Microsoft 365 looks for RDNS, SPF, DMARC and DKIM
Make sure all these are published properly. I have few client using Microsoft 365 no issues reported till date.
For one client I had to remove DMARC & DKIM and mail flow worked.
Like @Adrian Fretwell mentioned checking and comparing headers of both.
Try using an SMTP Provider like smtp2go or sendgrid and see if that makes any difference.

 

[Adrian Fretwell]

@mcs3ss2 Of course RDNS - sometimes we forget to state the very obvious! I get all the DMARC reports but I didn't know Microsoft 365 actually checked for it.

We learn something new every day...