I see this all the time on O365 accounts, it's been a very unreliable service for years from what I've observed.
I've seen this caused both from MS rate limiting their cloud products such as Exchange Online / O365 and from problems within their internal services (I've seen NTP, DNS and other problems between internal MS servers used for O365). As far as a fix goes, I'm assuming it's a paid / licensed service so I would suggest contacting O365 support with as much diagnostic information as possible in the hope that they don't give you the usual 'reinstall your mail client' line. -- Sam McLeod (protoporpoise on IRC) https://smcleod.net https://twitter.com/s_mcleod Words are my own opinions and do not necessarily represent those of my employer or partners. > On 20 Feb 2018, at 1:25 pm, Shane Chrisp <sh...@2000cn.com.au> wrote: > > Hi All, > > Is anyone else seeing issues with delivering mail to O365? We have been > seeing a steady stream of problems for the last hour with errors > > Deferred: 451 4.7.500 Server busy. Please try again later > > and also > > Deferred: 452 4.5.3 Too many recipients (AS780090) > > -- > Regards > > Shane Chrisp > 2000 Computers & Networks Pty Ltd > U8, 19 Outram St, West Perth, WA 6005 > Ph 08 6298 7391 Fx 08 6298 7393 > Mb 0412 409 856 > Email sh...@2000cn.com.au > Web http://www.2000cn.com.au > > _______________________________________________ > AusNOG mailing list > AusNOG@lists.ausnog.net > http://lists.ausnog.net/mailman/listinfo/ausnog
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