Office 365 outlook - All outgoing emails blocked as spam - Microsoft Community

hello,

i have office 365 email account (i'm admin), newly registered custom domain. i'm using outlook's webmail: outlook.office.com.

all outgoing emails blocked spam, including test valid @hotmail address.

i able receive emails.

this message receive "microsoft outlook" <*** email address removed privacy ***> :

delivery has failed these recipients or groups:

*** email address removed privacy *** (chady********@hotmail.com)
your message wasn't delivered because recipient's email provider rejected it.

diagnostic information administrators:

generating server: ***********.eurp192.prod.outlook.com

*** email address removed privacy ***
remote server returned '550 5.7.501 service unavailable, client host blocked using spamhaus. request removal list see http://www.spamhaus.org/lookup.lasso (as16042849)'

original message headers:

authentication-results: hotmail.com; dkim=none (message not signed)   header.d=none;hotmail.com; dmarc=none action=none header.from=chadiik.com;  received: ***********.eurp192.prod.outlook.com (***********)   ***********.eurp192.prod.outlook.com (***********) microsoft smtp   server (version=tls1_2, cipher=tls_ecdhe_rsa_with_aes_128_cbc_sha256_p256) id   ***********; tue, 25 jul 2017 22:07:36 +0000  received: ***********.eurp192.prod.outlook.com   ([***********]) ***********.eurp192.prod.outlook.com   ([***********%15]) mapi id ***********; tue, 25 jul   2017 22:07:36 +0000  content-type: application/ms-tnef; name="winmail.dat"  content-transfer-encoding: binary

i suspected automatically inserted "winmail.dat"; such, tried:

1. removing email signature: maybe cause of "winmail.dat" attachment, used microsoft word overcome rudimentary signature options within outlook. no
2. converting email 'text only', within message editor , through settings pane. (the settings navigation/ui nightmare way). no luck either

--

• please don't suggest whitelist address spamhaus, other email providers using other filters: not solution.
• once again: i'm not using pc client, i'm using outlook's webmail. tried both windows 10, , android devices.
• just in case, haven't tried setting thunderbird, avoid solution if possible: able check in , reply pc or device.
• i'm able send same address (to myself).
• email forwarding working.

thank you,

chady

hi alan,

thank quick reply.

the issue resolved overnight.

possible explanation (?):

i believe happened because of trying add rtf signature, coming microsoft word.

even if had removed signature, disabled it, , converted message "text only". still had issue.

maybe caching issue, cleared x hours later? explanation sensible?

i checked message source of sent email message today, , found no trace of "winmail.dat".

my new signature copy of formatted html content, , working fine.

my issue resolved, now.

thank suggestions , help.

regards,

chady

Office / Office 365 for business