Incoming email not being received

[saikarthik]

I don't see any incoming emails, not even in the logs. No errors either. They used to work until suddenly it stopped. Outgoing emails are fine. Where should I begin to troubleshoot?

[robi]

send yourself an email from another account or work with a friend.

[saikarthik]

@robi Yes, I tried that and I did not receive any emails. Nothing in logs, the space the mailbox occupies doesn't increase either.

[robi]

The point was to check the sending email client for errors in sending or bounces, etc.

Sounds like your DNS and MX records aren't pointing to the right place if nothing is happening on either end. They're going somewhere else with no errors.

[girish]

@saikarthik Incoming mail requires inbound port 25 to be open. You can debug this like:

• First, host -t MX domain.com (on check the MX record of your domain). Is this domain correct ?
• Second, telnet <above-record-value> 25 . This connects to port 25 of your mail sever. Does it connect ?

You can also check if you have enabled incoming port 25 in your firewall/security group.

[saikarthik]

@robi No errors on sender side either.

I ran the auto-setup of DNS through cloudron and no luck.

@girish first returned: domain.com mail is handled by 10 mail.domain.com. I see the same in my DNS settings. Second, however, returned mail.domain.com: nodename nor servname provided, or not known

Incoming port 25 is enabled on AWS security group.
Any ideas?

[girish]

@saikarthik maybe the telnet command you entered is wrong. It will look like this:

$ telnet my.smartserver.io 25
Trying 5.75.134.144...
Connected to my.smartserver.io.
Escape character is '^]'.
220 my.smartserver.io ESMTP Haraka ready

[DualOSWinWiz]

If domain is either on cloudflare or any similary than probably proxy is enabled for that account which needs to be disabled

[saikarthik]

@girish these were my results:

~ > host -t MX x.io                                                                                   INT 08:51:01 AM
x.io mail is handled by 10 mail.x.io.

~ > telnet mail.x.io 25                                                                                   08:51:03 AM
mail.x.io: nodename nor servname provided, or not known

~ > telnet my.x.io 25                                                                                     08:51:07 AM
Trying 5.16.22.1...
telnet: connect to address 5.16.22.1: Operation timed out
telnet: Unable to connect to remote host

The value set on cloudron UI for "Mail Server Location" was "mail". After I removed it to use the default, this started working again. Not sure of the primary reason for this issue.

[saikarthik]

Now I am seeing another error while trying to use email clients.

The identity of my.x.io cannot be verified. The certificate for this server is invalid. 

Do I just need to wait for DNS propagation since I updated the mail domain which triggered re-do of DNS?

[girish]

@saikarthik said in Incoming email not being received:

mail.x.io

I would also check host mail.x.io . Does this resolve to the IP address of Cloudron ? If you are using manual DNS, you have to add this DNS entry manually into your DNS. Otherwise, you can also Domains -> Sync DNS and it will add that A record DNS entry for you.

Another note: for mail clients (thunderbird, k9 etc) to connect, you have to open port 993 for IMAP and 587 (STARTTLS) and 486 (TLS) in your security group.

[saikarthik]

@girish Yes it resolves correctly to the Cloudron IP.

All required ports are open. I didn't have 486 but added it and tested and still no luck. Using email client used to work btw! I completely removed my account from Apple Mail and re-added and it worked after I ignored the certificate invalid warming. Screenshot 2023-10-01 at 11.28.48 AM.png

[girish]

@saikarthik said in Incoming email not being received:

it worked after I ignored the certificate invalid warming

This shouldn't be needed, I wonder if the email server is not valid? I would do Domains -> Renew all Certs and then also Services -> Mail -> restart for good measure. I can't verify the mail server cert without knowing your mail server domain, but if you would like me to verify you can send a mail to support@cloudron.io .

Otherwise, you can verify using openssl s_client -connect mail.domain.com:993 -crlf -quiet . This will print Let's Encrypt as the cert.

[saikarthik]

@girish The reason I saw these issues was because after I made Cloudron re-do my DNS, the root domain cert was also replaced which was separately hosted on netlify. I believe this is what triggered the cert warning. I had to re-add the entry for netlify load balancer in my DNS.

[necrevistonnezr]

@saikarthik said in Incoming email not being received:

I had to re-add the entry for netlify load balancer in my DNS.

Maybe next time lead with that. The use of „netlify load balancer“ seems to be some vital information while people are trying to guess-troubleshoot your DNS problems….