Authentication unsuccessful using smtp except for - Microsoft Community

hello everybody,

my name fernando , system administrator. 

our company using office365 online exchange system.

i have several applications must authenticate against smtp.office365.com or smtp.outlook.com in order send emails (backup applications, servicedesk application, web applications...) lately not able authenticate against smtp servers, , so, emails not being sent.

this starting impact our business because our clients not getting response our automated tools.

i have been able detect applications able authenticate (barely) , when end authenticating against:

[string].eurprd07.prod.outlook.com

if other server handles authentication, answer authentication unsuccessful.

here list of servers not letting authenticate:

authentication unsuccessful [vi1p193ca0011.eurp193.prod.outlook.com]

authentication unsuccessful [he1pr0901ca0050.eurprd09.prod.outlook.com]
authentication unsuccessful [db6pr0601ca0024.eurprd06.prod.outlook.com]

authentication unsuccessful [db6pr0601ca0019.eurprd06.prod.outlook.com]
authentication unsuccessful [am6pr0402ca0030.eurprd04.prod.outlook.com]
authentication unsuccessful [he1pr0501ca0042.eurprd05.prod.outlook.com]
authentication unsuccessful [am5pr0402ca0021.eurprd04.prod.outlook.com]
authentication unsuccessful [am5pr0402ca0013.eurprd04.prod.outlook.com]
authentication unsuccessful [db6pr0402ca0012.eurprd04.prod.outlook.com]
authentication unsuccessful [db6pr0402ca0003.eurprd04.prod.outlook.com]
authentication unsuccessful [cwxp265ca0015.gbrp265.prod.outlook.com]
authentication unsuccessful [db6pr0301ca0016.eurprd03.prod.outlook.com]
authentication unsuccessful [am4pr0902ca0004.eurprd09.prod.outlook.com]
authentication unsuccessful [db6pr0301ca0023.eurprd03.prod.outlook.com]
authentication unsuccessful [am4pr0902ca0020.eurprd09.prod.outlook.com]

....(the list way longwer)...

now, have no problem log in owa or outlook client.

the applications using system until month , never had issue before.

tried increase timeouts, verify passwords, , way make things work change mail provider (tried , worked).

the accounts facing issue different , thing in common belong our domain.

i appreciate or if in wrong channel communicate, love know right place it.

thank in advance,

fernando

if office365 business customer should opening support ticket through admin center. that's best way these kind of issues solved.

Outlook.com / Email / Sending, receiving, and reading email