Hello
I will cut all info about user emails IP/Hosts - cause I don't like paste information like that on public forums - If you need any information send me private message.
Let's start from beginning to clear situation:
Around 2,5 week ago my company changed location where get new ISP and new IP address.
After setting all things up (only IP changes on server) after some time we got blacklisted cause DUL on some RBL-s (wrong information - ISP assign static IP on marked dynamic class).
I contacted with all RBLs lists where we was blocked and my company is not listed anywhere (I think i checked all global lists).
When we tried send mails to our branch office (hosted in Microsoft 365) - my server providing information like that....
<user@mydomain.at.microsoft>: host xxx.mail.eo.outlook.com[216.32.181.178]
said: 550 5.7.1 Service unavailable; Client host [xxx.xxx.xxx.xxx] blocked
using Blocklist 1, mail from IP banned; To request removal from this list
please forward this message to delist@messaging.microsoft.com and include
your ip address <CUT> . (in reply to RCPT TO command)
Then I send there NDR and other informations, but my comapny is still blocked.
So to check it I asked again and I get information:
"It appears that the IP you submitted is not currently listed on any of our block lists. This may be due to an earlier delisting request that has already been processed."
"Regarding your issue, Non-Delivery Receipt (NDR) provided by you does not indicate IP address or domain being blocked. Hence kindly create a service request using FOPE Account or support.microsoft.com and you may also call us <cut>"
After first delist contact only reason of block changed:
Delivery has failed to these recipients or groups:
admin@domain.onmicrosoft.com<mailto:admin@domain.onmicrosoft.com>
Your message wasn't delivered due to a permission or security issue. It may have been rejected by a moderator, the address may only accept e-mail from certain senders, or another restriction may be preventing delivery.
Diagnostic information for administrators:
Generating server: bigfish.com
#550 5.7.1 Access Denied, bad mailhost ##
Original message headers:
<cut>
Cause I don't have administrator account at our branch office (we outsourced IT there) and I can't use FOPE account to check anything I created trial account at Office 365 to check that problem from other side - and eliminate that is not an account specific problem and get exactly same NDR (only email changed), then I tried contact to other peoples what have accounts in Office 365 - and i got same NDR.
I used inbound/outbound "Internet E-Mail Tests" for Office 365 at https://www.testexchangeconnectivity.com and they all seems good (all green everywhere).
So my company is blocked without any specific reason or information why - from our side information "bad mailhost" tell us nothing.
Like i said before i can provide all information what you need to resolve that problem just contact with me.