Hi,
I use Thunderbird normally. But I recently sent an email to multiple addresses, each with an attachment taken from Libre Writer. But they did not go - I got a panel saying 'error occurred while sending message:
550 (my email address) sender rejected invalid domain no (MX or A record)'

I tried a couple more times and got the same. To check if it was a problem with Thunderbird, I downloaded Sylpheed and tried that. No luck. I got
'error occurred while sending mail. the mail server responded: lyxheaknll message rejected by diel (i think) to S or V'

I'm not sure I've read the scribbles on my bit of paper correctly so I hope someone can do a bit of interpreting and help me out here.

Thanks in advance
cleafell

It DNS-speak. The MX and A records are different types of dns records. Don't quote me, but I think mx is a mailer record, and A is address mapping.

What's in /etc/resolv.conf? Is the address that thunderbird is puking in valid? There's online dns checkers, or you have nslookup or dig on any linux box.

tony@tony-System-Product-Name ~ $ sudo /etc/resolv.config
[sudo] password for tony:
sudo: /etc/resolv.config: command not found
tony@tony-System-Product-Name ~ $ nslookup
>
Well,that's what I got and it means nothing to me. I have tried sending the email message and attachment to more than one email address so I think it unlikely that all of them would be invalid.
I'll play about online by googling in dns checkers. This will have to be tomorrow now as it's getting on for midnight here. I'll let you know what I find.

we want to see the contents of the file. It's not a command.
The 550 error is saying that your email provider has no MX (mail server) record. Are you running the mail server yourself?
OR the From: email setting in Thunderbird is corrupted and the @somedomain.com part is not a valid domain.
Does email go through without attachments?

I thought I'd do a quickie and found dnscheck.pingdom.com. It checked my johnlewisbroadband.com and found that all parameters, Delegation, Nameserver, Consistency, SOA, Connectivity and DNSSEC were fine. Hmm

See if you can think of something else,please, business kid. I'll check first thing tomorrow morning.
Cheers.

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 127.0.1.1

For the first time ever,I've poked about in the file ssystem. I'm amazed at the depth and complexity of it all. Is the above any use?

Error occurred while sending the message:
550 <betula@john-lewis> sender rejected - invalid domain (no MX or A record)

When I tried to send an email, without attachment, Sylpheed queried if I wanted to send it. When I said yes I got the above. I'm not running the server myself - it's about all I can do to turn the computer on!
My sever is relay.johnlewisbroadband.com

127.0.0.1? Are you using your own dns server? If so, it's borked.

Try this as root Then try sending the mail. Somewhere either your router or your network should be providing dns servers to you, but they're not. What's your distro?

The distro is Linux Mint. Something else is now borked. The Terminal now won't recognise my password. I've tried su and sudo without success. Is there a way I can change my root password and then start using that?

We haven't gone near password stuff. Search on a Mint forum, I suggest. Or reboot on the install cd, and mount it's / dir somewhere if the install hasn't mounted it, and chroot into it from the install cd

e.g. mount /dev/sdaX /mnt
chroot /mnt

Then you can run passwd, e,g.
/usr/bin/passwd <whoever>

and exit gracefully.

Hi again,
I got myself in a real pickle there so I've taken the path of least resistance. I've re-installed my operating system and all looks well now.
Thank you both for posting in an attempt to help me. Much appreciated.
Clearfell

Yeah, that sets it up. Pity about any updates. I usually take that as a defeat because I am missing out on a chance to learn something, but I'm getting more sense lately. I suppose mark this solved.