topic Re: unable to send or receive e mails in Email

unable to send or receive e mails

safcdl16 — Mon, 23 Feb 2026 08:31:50 GMT

I am unable to send or receive e mails and am getting this error message ;

SMTP Error (550): Failed to set sender -then lists my e mail address-(5.7.1 Unknown sender).

Re: unable to send or receive e mails

MisterW — Mon, 23 Feb 2026 09:18:04 GMT

@safcdl16 has your email been migrated to Greenby ?

Re: unable to send or receive e mails

safcdl16 — Mon, 23 Feb 2026 09:27:23 GMT

I thought everyone's had. How would I know/check ?

Re: unable to send or receive e mails

MisterW — Mon, 23 Feb 2026 14:33:39 GMT

No, migration is being done in stages. If you've been migrated you should have received an email to your default address.

Does the address you are sending from exist as a vaild mailbox name ?

Re: unable to send or receive e mails

safcdl16 — Tue, 24 Feb 2026 11:16:10 GMT

Sorry, I'm not good with techy stuff and not sure I understand this - Does the address you are sending from exist as a vaild mailbox name ?

If you mean my plus net address- yes itnis valid in that it is the one listed as the current postbox in my webmail inbox. I have had no notifications from anyone but it appears I've had no e mails to this little used inbox for some time.

Re: unable to send or receive e mails

MisterW — Tue, 24 Feb 2026 14:31:52 GMT

Sorry, I'm not good with techy stuff and not sure I understand this - Does the address you are sending from exist as a vaild mailbox name ?

Ok, to explain, say you have a mailbox called fred , then the email address would be fred@<accountname>.plus.com.

Because most accounts have a catch-all mailbox, some people will 'invent' other email addresses say joe@<account>.plus.com even though no mailbox exists for joe, on the basis that email for joe will be received to the catch-all mailbox.

Whilst this will work when the email is still hosted by Plusnet, it seems that once migrated to Greenby, sending mail from addresses that arent mailbox names, gets rejected.

Re: unable to send or receive e mails

safcdl16 — Wed, 25 Feb 2026 07:26:44 GMT

Thank you, MisterW, this makes so much sense now and seems to be where my problem lies (I think).

I have a "postmaster @" address and thought I was using that to differentiate between mails for me and my Granddaughter's season ticket info. I had noticed that the sign in for "postmaster" was failing but , as it allowed me to sign in as "account" , I didn't bother (assuming the inbox was amalgamated as I hardly ever get stuff for myself there). Now you've flagged the issue I can confirm that even though I'm signing in as "account" the inbox is defaulting to "postmaster" and that is the one which can't send or forward mails or receive new mails.

Or I may just be showing how thick I really am.

Re: unable to send or receive e mails

MisterW — Wed, 25 Feb 2026 07:53:46 GMT

We need to check if you've been migrated to Greenby. You should have been sent an email advising of the transfer but there's anecdotal evidence that some have gone astray!

Can you try logging in to the Greenby portal at greenby.com. Use you Plusnet account name and password and (assuming you have a <account>.plus.com email address ) select Plusnet as the provider.

Let us know if you can login

Re: unable to send or receive e mails

safcdl16 — Wed, 25 Feb 2026 11:07:25 GMT

Thank you. I'm tied up today but will get onto Greenby tomorrow.

To confuse the issue (told you 😞) I "manage" an account for my Mother in law in the same way. She hasn't had any migration e mail either.

She is only receiving mails to her "name" mailbox. I've sent mails to both her "name" and "account" and only the "name" received it. I can sign into both mailboxes. The "account" mailbox gets the same error message as this original query but the "name" outgoing mail got this undelivered mail response

This is the mail system at host gateway1.enmail.co.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The mail system

I'll take both accounts up with Greenby and update when I can.