Outgoing server (SMTP) smtp.office365.com is unknown

[archeon]

Hi,

since a few days I am not able to sent emails using my work email account from my home network.  I receive the error message "Outgoing server (SMTP) smtp.office365.com is unknown".  The SMTP server uses the port 587 and STARTTLS.

It is not an issue with my email client or my account settings nor outgoing mail in general since I am able to sent emails from my laptop at work or from other networks  and I am able to sent emails using my private email account from home.

I also understand that Verizon supports the port 587, thus I am a bit lost as to what the problem could be, especially since it worked before and I have not changed anything.

Any suggestions?

Thanks

[eljefe2]

You might try changing the outgoing port to 465 and see if that corrects the problem.

[tns2]

Problem probably has nothing to with verizon.

Is smtp.office365.com a Microsoft mailing server?  If so ask them.  Either way find someone responsible for the server you are having trouble with.

ps verizon's servers will no longer support 587(something they have said for a couple years now and about to enforce), but they don't block you from using it to other servers.

[archeon]

Thanks,

but unfortunately it is either verizon or my router. since with the same machine I have no trouble sending emails from that account if I am outside of my home.   However, I have not changed anything nor touched the router.

[archeon]

Thanks

Tried it, but did not work.

[gs0b]

Open a command prompt and enter "ping smtp.office365.com".  You should see something like this:

   C:\Users\gs0b>ping smtp.office365.com

   Pinging outlook-nameast.office365.com [132.245.12.18] with 32 bytes of data:
   Reply from 132.245.12.18: bytes=32 time=59ms TTL=245
   Reply from 132.245.12.18: bytes=32 time=58ms TTL=245
   Reply from 132.245.12.18: bytes=32 time=58ms TTL=245
   Reply from 132.245.12.18: bytes=32 time=58ms TTL=245

   Ping statistics for 132.245.12.18:
       Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
   Approximate round trip times in milli-seconds:
       Minimum = 58ms, Maximum = 59ms, Average = 58ms

If you don't get the first line that shows the IP address of smtp.office365.com, you have a problem with DNS.  I use OpenDNS.

Good Luck.