Welcome to Comcast Help & Support Forums
Find solutions, share knowledge, and get answers from customers and experts

New to the Community? Start here.

5,805,474

members

52

online now

1,951,915

discussions

Top

Delivery failure - SMTP error 421

New Poster

Delivery failure - SMTP error 421

We have two people with comcast.net email addresses which have been added to a distribution list on our corporate email (Office 365 Exchange).  A test message to them last night resulted in the following error:

 

6/21/2016 6:30:28 AM - Server at comcast.net (2001:558:fe21:2a::6) returned '450 4.4.317 Cannot connect to remote server(421 resimta-ch2-15v.sys.comcast.net comcast Try again later)'

 

I'm interpreting this as your external gateway is accepting the main, but the next-hop server is refusing the connection when it tries to pass the message along. Do you agree with this analysis?

 

If not, what is the root cause of this error?

 

If so, how can I check to see whether has the issue been resolved?  

 

Thanks!

Official Employee

Re: Delivery failure - SMTP error 421


KenFischer wrote:

We have two people with comcast.net email addresses which have been added to a distribution list on our corporate email (Office 365 Exchange).  A test message to them last night resulted in the following error:

 

6/21/2016 6:30:28 AM - Server at comcast.net (2001:558:fe21:2a::6) returned '450 4.4.317 Cannot connect to remote server(421 resimta-ch2-15v.sys.comcast.net comcast Try again later)'

 

I'm interpreting this as your external gateway is accepting the main, but the next-hop server is refusing the connection when it tries to pass the message along. Do you agree with this analysis?

 

If not, what is the root cause of this error?

 

If so, how can I check to see whether has the issue been resolved?  

 

Thanks!



Can you please private message me the complete deferral message you're seeing?  Full headers if possible.

 

Thanks,


ComcastDaveL

 

PS -

 

On the side of each forum posting, if you click on the poster's name, you can send them a private message.

 





Community Icon
I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: Product, Support, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am an Offical Comcast Employee.
Official Employees are from multiple teams within Comcast.
We ask that you post publicly so people with similar questions may benefit.
Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am a Comcast Employee.
Please post so people with similar questions may benefit.
Was your question answered?
Mark a Best Answer!solution Icon

New Poster

Re: Delivery failure - SMTP error 421

I seemed to have come across this same problem since 7/4/16.  Has there been a resolution to your problem?  I've had my outlook email settings working for years and just now it has stopped working and I am unable to send any emails.  My error is the same with 421 but the message says  421 resomta-po-02v.sys.comcast.net comcast Too many sessions opened'.  Seems like a code bug to me.

Official Employee

Re: Delivery failure - SMTP error 421

This should now be resolved, there was a configuration issue with some of our outbound MTAs and seems you were caught in the mix.  Apologies for the inconvenience.





Community Icon
I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: Product, Support, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am an Offical Comcast Employee.
Official Employees are from multiple teams within Comcast.
We ask that you post publicly so people with similar questions may benefit.
Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am a Comcast Employee.
Please post so people with similar questions may benefit.
Was your question answered?
Mark a Best Answer!solution Icon

Regular Visitor

Re: Delivery failure - SMTP error 421

I am still seeing this same message...ESMTP server is not available. Please contact support. Comcast user support has not been helpful in the least (we had it three days in a row, but it seems to have worked occasionally...at night...just not the next morning)

 

Regular Visitor

Re: Delivery failure - SMTP error 421

This error is not fixed.  I keep running into it over and over.  It works fine for a while, then suddenly it gives me the error msg again - including today. 

Message says:  "One or more messages could not be sent. These messages are still in your Outbox, please correct them and then try again."  Usually when I click 'details' there are none, but today it says, "421 resomta-ch2-06v.sys.comcast.net comcast ESMTP server error (try again later)"

I'm using Incredimail if that makes a difference.  Settings are IMAP 993 and SMTP 587.

New Poster

Re: Delivery failure - SMTP error 421

I have been having the same error on all my devices for all my comcast accounts. , Apple, Android, Windows 8, 10 Outloook 7 Outlook 13 since July 17th for comcast smtp servers with pop3 mail.  It worked yesterday 7/22/16 for a bit not again today.  All my smtp servers with pop3 from other ISPs work fine.   Nothing was changed on any of my devices, routers, etc to cause this problem so it appears to be a problem on the comcast netwrok.  All devices, routers, cable modem have been rebooted.   Actual error receiving each time is 421 resomta ch2-12v.sys.c

 

Jay Farrug

 

New Poster

Re: Delivery failure - SMTP error 421

I suddenly started getting this message as well when I use Outlook this morning. I tried to repair the system and got this---

Send test e-mail message: The server responded: 421 resomta-ch2-15v.sys.c

 

Nothing has changed on my end -- no new password or anything.

 

Mail seems to be coming in, though not all of it! (and yes, I've checked the online spam file)

Official Employee

Re: Delivery failure - SMTP error 421


clueless44 wrote:

I suddenly started getting this message as well when I use Outlook this morning. I tried to repair the system and got this---

Send test e-mail message: The server responded: 421 resomta-ch2-15v.sys.c

 

Nothing has changed on my end -- no new password or anything.

 

Mail seems to be coming in, though not all of it! (and yes, I've checked the online spam file)


 

Looks ok as of a little while ago (from an IP in Boston, looks like), before that there were some authentication failures - from an IP in Korea.  If you're not in Korea, it would be a good idea to change your password, just in case.

 

ComcastDaveL





Community Icon
I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: Product, Support, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am an Offical Comcast Employee.
Official Employees are from multiple teams within Comcast.
We ask that you post publicly so people with similar questions may benefit.
Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am a Comcast Employee.
Please post so people with similar questions may benefit.
Was your question answered?
Mark a Best Answer!solution Icon

New Poster

Re: Delivery failure - SMTP error 421

okay I changed my password and that was a success because I can get into my account here online. but in Outlook I'm still getting this mesage


Task '[my name]@comcast.net - Sending' reported error (0x800CCC67) : ' The server responded: 421 resomta-ch2-02v.sys.comcast.net comcast ESMTP server temporarily not available, please contact support'

 

ALSO other email seems to not be showing up even here online so it's now affecting the inbox, not just the out.

New Poster

Re: Delivery failure - SMTP error 421

okay incoming box seems okay but still no outgoing messages. still getting this message:
Task 'd******@comcast.net - Sending' reported error (0x800CCC67) : ' The server responded: 421 resomta-ch2-15v.sys.comcast.net comcast ESMTP server temporarily not available, please contact support'

 

 

Official Employee

Re: Delivery failure - SMTP error 421


clueless44 wrote:

okay incoming box seems okay but still no outgoing messages. still getting this message:
Task 'd******@comcast.net - Sending' reported error (0x800CCC67) : ' The server responded: 421 resomta-ch2-15v.sys.comcast.net comcast ESMTP server temporarily not available, please contact support'

 

 


Can you let me know what https://www.whatismyip.com shows as your IP address?

 

Thanks,

 

ComcastDaveL





Community Icon
I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: Product, Support, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am an Offical Comcast Employee.
Official Employees are from multiple teams within Comcast.
We ask that you post publicly so people with similar questions may benefit.
Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am a Comcast Employee.
Please post so people with similar questions may benefit.
Was your question answered?
Mark a Best Answer!solution Icon

Contributor

Re: Delivery failure - SMTP error 421

I'm having outbound message failures and I've been through all settings with two Comcast support people.  I've also rebooted all hardware in my home network.  I'm getting a "421 resomta-po-07v.sys.commcast.net ESMTP server temporarily mot available.." message  and a "421 resomta-po-16v.sys.comcast.net ESMTP server temporarily mot available..." message for my two (POP3 and IMAP) clients.   What's going on?   This is new as of a week or so ago.

New Poster

Re: Delivery failure - SMTP error 421

I get the same error when sending from Outlook 2013.  Email gets stuck in my outbox.

 

Error Msg:

Task 'myname@comcast.net - Sending' reported error (0x800CCC67) : '  The server responded: 421 resomta-ch2-13v.sys.comcast.net resomta-ch2-13v.sys.comcast.net Excessive failed authentication, ESMTP server temporarily not available, please contact support'

 

My wife has had the same problem in the last week or so, but on and off.  Today my outbound emails when immediately without being held in the outbox.  No problem receiving emails.

 

I tried to use Comcast Chat but gave up after 15 min waiting with the circle kept running. 

Official Employee

Re: Delivery failure - SMTP error 421

I'll send a private message with further details about what might be causing this.  Give me a few minutes.





Community Icon
I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: Product, Support, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am an Offical Comcast Employee.
Official Employees are from multiple teams within Comcast.
We ask that you post publicly so people with similar questions may benefit.
Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am a Comcast Employee.
Please post so people with similar questions may benefit.
Was your question answered?
Mark a Best Answer!solution Icon

New Poster

Re: Delivery failure - SMTP error 421

no reply from you. Nor any private msg.  Out going email not working again this PM.

Official Employee

Re: Delivery failure - SMTP error 421

I did send it, there's no notification in the upper right corner? I can resend if you don't see it





Community Icon
I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: Product, Support, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am an Offical Comcast Employee.
Official Employees are from multiple teams within Comcast.
We ask that you post publicly so people with similar questions may benefit.
Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am a Comcast Employee.
Please post so people with similar questions may benefit.
Was your question answered?
Mark a Best Answer!solution Icon

New Poster

Re: Delivery failure - SMTP error 421

I have been getting this same issue now for well over a year. Works one day, doesn't work the next. I get to level 3 support and they send me on a wild goose chase. I wish they would solve the problem. They need to own it first.

New Poster

Re: Delivery failure - SMTP error 421

Just started having this issue today for no apparent reason. I've tried support who have escalated my call but it sounds as though this is an issue that there is no solution for. 

Contributor

Re: Delivery failure - SMTP error 421

When an email client repeatedly fails authentication, Comcast blocks the sending IP address. After a time (12 hours maybe?) Comcast lifts the block, automatically I think.  Check every device in your network that might be trying to send outbound email. If one has the outbound (SMTP) password setting wrong, or the wrong port, then authentication will fail. Too many fails=blocked.

Official Employee
Moved:

Re: Delivery failure - SMTP error 421

New Poster

Re: Delivery failure - SMTP error 421

Im getting a error in Outlook and I have called support over and over and no help. They wont even create a ticekt for me, they just send me an email. This is the currect error im getting although it changes from day to day.

 


Task 'j-----c-----@comcast.net - Sending' reported error (0x800CCC67) : ' The server responded: 421 resomta-ch2-06v.sys.comcast.net resomta-ch2-06v.sys.comcast.net Too many sessions opened'

 

(address above edited by comcast admin to prevent harvesting by spammers)

Official Employee

Re: Delivery failure - SMTP error 421


jennycustomshad wrote:

Im getting a error in Outlook and I have called support over and over and no help. They wont even create a ticekt for me, they just send me an email. This is the currect error im getting although it changes from day to day.

 


Task 'j-----c-----@comcast.net - Sending' reported error (0x800CCC67) : ' The server responded: 421 resomta-ch2-06v.sys.comcast.net resomta-ch2-06v.sys.comcast.net Too many sessions opened'

 

(address above edited by comcast admin to prevent harvesting by spammers)


 

jennycustomshad-

 

If you go to http://whatismyip.com, does it show your IP address as 2601:483:c400:941f:7479:173a:e8a0:df40 ?

 

Something coming from that IP keeps failing SMTP Authentication.  You may want to double check your Outlook settings, or login to https://xfinity.com  webmail, and reset your password, before changing the password in Outlook to match.

 

Hope this helps,

 

ComcastDaveL





Community Icon
I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: Product, Support, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am an Offical Comcast Employee.
Official Employees are from multiple teams within Comcast.
We ask that you post publicly so people with similar questions may benefit.
Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am a Comcast Employee.
Please post so people with similar questions may benefit.
Was your question answered?
Mark a Best Answer!solution Icon

New Poster

Re: Delivery failure - SMTP error 421

Hi Dave, 

 

I checked my IP and its different from the one you listed- 

Your IP Address Is:

30091facc:f7:d2
 
Also, I was able to change my PW but now Im getting a new error in outlook- 
Send test e-mail message: The server responded: 421 resomta-po-05v.sys.co
 
Thanks,
Jenny
New Poster

Re: Delivery failure - SMTP error 421

I am having the exact same problem.  It has been working for years and even this morning.  Just started a few hours ago.

 


Task 'f.hugh@comcast.net (1) - Sending' reported error (0x800CCC67) : ' The server responded: 421 resomta-po-17v.sys.comcast.net resomta-po-17v.sys.comcast.net Excessive failed authentication, ESMTP server temporarily not available, please contact support'

Official Employee

Re: Delivery failure - SMTP error 421

Bishopmax, I'm going to send you a private message with the information that should help.

 

Note to others, I'm going to lock this thread (if others are still subscribed, they're getting notifications for each update), and suggest that you send me a Private Message (click on my name) with the same subject. We'll work with you to get it figured out.

 

ComcastAlex





Community Icon
I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: Product, Support, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am an Offical Comcast Employee.
Official Employees are from multiple teams within Comcast.
We ask that you post publicly so people with similar questions may benefit.
Was your question answered? Mark a Best Answer!solution Icon
Community Icon
I am a Comcast Employee.
Please post so people with similar questions may benefit.
Was your question answered?
Mark a Best Answer!solution Icon