Recipients failed permanently

[Zingere]

Hi, I have two cousins in Pescia Italy that live in the same town with the same provider alice.it. I can't send mail to one of these addresses.
I receive a response that the recipient failed permanently. There is a very long and confusing message that I do not understand. Is there a way to correct what ever is causing the Permanent Error. I cant tell if it is my provider or their provider. This did work at one time a couple of years back. Then suddenly this error started. The response that I receive has a lot of code numbers and abbreviations and techy words that I do not understand. What can I do?

[DanRaisch]

The error would be on their provider's side.
Have you confirmed with your cousin that the email address you have for them is still valid?

[Zingere]

Yes their address is still good. If I send them through yahoo they receive the emails. Is it possible that their provider thinks that the message is spam?

[DanRaisch]

That is possible. Is there an attachment to the message you are trying to send them? If so, have you tried sending a simple message in text format with no attachment?

[Grumpus]

Having a similar issue.
I have three accounts. Two have been used for years and one is current with new provider (since 2019).
In order to send mail on the two older accounts the outbound server of the provider has been used successfully since 2019
Receiving mail on the older accounts does not appear to be an issue, private message notification from here as recent as a day ago showed.
But sending from those accounts using the provider's outgoing are blocked for some reason and
the permanent error message doesn't show up while sending on the providers email appears to go through with no error.

Below is the error message with the email blocked out

This is an automatically generated Delivery Status Notification.
Delivery to the following recipients failed permanently:
* xxxxxxx@gmail.com
Reason: Permanent Error
Reporting-MTA: dns; resqmta-a1p-077723.sys.comcast.net [96.103.146.34]
Received-From-MTA: dns; resomta-a1p-077251.sys.comcast.net [96.103.145.233]
Arrival-Date: Tue, 26 Apr 2022 12:08:13 +0000
Final-recipient: rfc822; xxxxxxx@gmail.com
Diagnostic-Code: smtp; 550-5.7.1 [2001:558:fd01:9 12] Our system has detected that this

Last-attempt-Date: Tue, 26 Apr 2022 12:08:13 +0000

Something appears to be missing in the diagnostic .
Emails sent in both html and also in plain text with no attachments.
These accounts, using the providers outbound have had no issues until this week.

[DanRaisch]

These accounts, using the providers outbound have had no issues until this week.

By "the provider's outbouond" do you mean sending from the provider's webmail page, or something else
Does the same error occur with any recipient? What happens if you send a message to your own email address(s)?

[Grumpus]

Mailing to/from my own emails worked fine. All accounts.
Mailing from the Comcast account functioned apparently (at least no error message yet)
The email accounts are from another network (lanset) but use the Comcast outbound smtp server. (none are web mail accounts)
This is the same smtp server for the Comcast email account which has been functioning since 2019, all worked fine through Thunderbird.
Checked the server settings and passwords for all accounts and everything appears to be as it should
Contacted Comcast but they apparently have limited information on the subject outside of Comcast.
Contacting Lanset is next but I'm thinking something is amiss with the server address. Appears right in the settings but is corrupted somehow.
This has been corrupted invisibly in the past and a complete re-install of Thunderbird was necessary for the fix.
I don't get junk or spam except on the Comcast account which appear to go right to junk, unread and I delete each one.

[Grumpus]

@ Dan Raisch - This appears to be solved at this point.
Problem lay on the recipients (Google) end and not with Comcast, Lanset or the Thunderbird settings.
Verification from Lanset which received a mailing properly and their response closes the issue.
Thanks.

[DanRaisch]

Thanks for letting us know, Grumpus.

[Grumpus]

UPDATE: Solution
Have tried several times to send and believe I've found the definitive issue.
For a number of years used a private mail service instead of Gmail or the ISP's mail account.
Incoming works fine on the two private accounts and the ISP's account but outgoing does not when emailing to Gmail accounts.
Incoming is used for the private accounts but the outgoing uses the ISP's secured server. apparently Gmail objects to this.
It works fine with other outgoing addresses just not Gmail. Believe it is an anti-spam device.

[Grumpus]

Update II:
It appears a number of emails using email address A but going out on email address B server will be blocked automatically by various ISPs or networks.
Noticed this occurs with Gmail and what ever mail The Register uses. Emails still go where this is not deployed.
Initially thought it was my ISP but emails sent to me from Address A through the B address go through and also to the email provider of address A using the B address.
While it makes some sense to cut down on spam where a fictitious email address uses a compromised out going server it causes consideration of privacy issues.

[tanstaafl]

Many ISPs smtp servers have a poor reputation spam wise. I used blacklist: smtp.comcast.net at https://mxtoolbox.com/SuperTool.aspx to check how many blacklists Comcasts smtp server is on.

[Grumpus]

Makes sense as most of the bogus IPs in the monitor come from compromised Comcast servers.
Blocking them doesn't help all the time.
Considering the advertising Xfinity runs this makes their security clams completely false.
Thanks for the insight.