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421 problem with outlook

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New Poster

421 problem with outlook

I ca receive emails but
Can NOT send
Get code 421
Can someone help a poor
Old man?
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Gold Problem Solver

Re: 421 problem with outlook

We'd need the text that goes along with the error code, as 421 is associated with several different error conditions, ex:

  • 421 - Too many sessions opened
  • 421 - Reverse DNS failure
  • 421 - Try again later

See https://postmaster.comcast.net/smtp-error-codes.php#421.

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Gold Problem Solver

Re: 421 problem with outlook


@Jarita wrote: ... CSI IP 172.102.178.157 is not permitted to send messages. ...

CSI in the error message means the listed IP is blocked by Cloudmark Sender Intelligence. 172.102.178.157 is assigned to Ellijay Telephone Company / ETC Communications (see https://whois.arin.net/rest/net/NET-172-102-160-0-1). Please see https://forums.xfinity.com/t5/Email-Web-Browsing/Can-t-Send-Emails-from-PC-or-Phone-App/m-p/3355422#.... Are you using a VPN?

 

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New Poster

Re: 421 problem with outlook

not using VPN

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Gold Problem Solver

Re: 421 problem with outlook


@Jarita wrote: not using VPN

Are you trying to send while using another ISP?