email receiving but not sending

[#1]

I am using Outlook 2007 and Windows 8.1 on a PC

I tried sending an email this morning and got the following error message:

Task 'name@myname.plus.com - Sending' reported error (0x800CCC78): 'Cannot send the message. Verify the address in your account properties. The server responded: 550 <name@myname.plus.com> sender rejected - invalid domain (no MX or A record)

I Googled the error number (0x800CCC78) and that gave me a number of options to do with settings. I haven't changed any of the settings in about five years so there is no reason to suspect them. another option was to do with *.pst files and that seemed a possibility since files can get corrupted any time.

I downloaded a pst repair tool and repaired my pst files (plural) but I can still not send email.

I am not an expert on this but am a little confused as to why I should have more than one pst file. I have three, one of them is called archive, but that still leaves me with two pst files, and I can't confirm that I have always had more than one so I don't know if this is even relevant, but it seems worth mentioning.

I can confirm that in Windows Explorer the Date Modified field for all three of them updates as the programme accesses them, so Outlook knows they are there and is using them.

but I can't send email.

any ideas what I should try next,

many thanks,

Kaarlo Tuomi

[#2]

Me too. I can send on a GMail account but not my Plusnet one. I am receiving on Plusnet. I am using Thunderbird under windows 11 and get the warning :-

Sending of the message failed.
An error occurred while sending mail. The mail server responded: <xxx@xxx.plus.com> sender rejected - invalid domain (no MX or A record). Please verify that your email address is correct in your account settings and try again.

Why do I have this forum in my favourites ? (Because I use it so much)

[#3]

Sounds like the email platform is borked - again. Needs reporting when they open.

[#4]

Experiencing same problem. Server says: "Sending' reported error (0x800CCC78) : 'Cannot send the message. Verify the email address in your account properties. The server responded: 550 ....sender rejected - invalid domain (no MX or A record)"
Domain problems resulted from the May 10 Windows updates.  Microsoft issued an emergency patch which Plusnet may not yet have applied.

[#5]

Nope, @redsox9 - it is definitely a PlusNet mail-server problem, I am with another ISP, using a mail-only account on Linux, so it is not Windows - this time.

[#6]

Same problem here. How and when can I report?

Alex.

[#7]

@ceresian Ring in after 0900 on 0800432 0200

[#8]

Now receiving/sending email normally.

[#9]

All good here again, thanks everyone!

Alex.