Request for Assistance with Outgoing SMTP Email Delivery from My Server

Support and Discussion
1

Ubuntu 22.04.5 LTS
Current Version: 2.3
Build: 8
Current Commit: 1dc3c9d8aaaf2d973842f34febd45b7738199519
Latest Version: 2.4
Latest Build: 2
Latest Commit: eb0b01d8b158d2dfa6de334e94e021fbb3532f4f

I am reaching out regarding email delivery issues from my server associated.

I have conducted extensive connectivity and TLS tests to the MX servers of my domain using the CheckTLS service, and all tests confirm that:

  • Outgoing connections to the SMTP port 25 on Google MX servers (smtp.google.com) are successful.
  • TLS and certificates are properly validated.
  • The servers respond correctly to SMTP commands.

Despite this, I am experiencing problems sending emails from my server.

Could you please check if there are any network restrictions, firewall rules, or filtering policies on my hosting or server that might be interfering with outbound SMTP traffic or email delivery?

If you require any additional information or logs from my side to diagnose the problem, I will be happy to provide them.

Thank you very much for your support.

postfix/smtp[pid]: connect to smtp.gmail.com[IP]:587: Connection timed out
postfix/smtp[pid]: connect to smtp.gmail.com[IPv6]:587: Network is unreachable

seconds lookup result
[000.001] DNS LOOKUPS
[000.002] SEARCHLIST 168.63.129.16,1.1.1.1,8.8.8.8
[000.717] MX–>funpadel.pt (1) smtp.google.com
[000.727] MX:A–>smtp.google.com 64.233.180.26
[000.727] MX:A–>smtp.google.com 142.251.179.26
[000.727] MX:A–>smtp.google.com 142.251.179.27
[000.728] MX:A–>smtp.google.com 172.253.62.26
[000.728] MX:A–>smtp.google.com 172.253.62.27
seconds test stage and result
[000.000] Trying TLS on smtp.google.com[64.233.180.26:25] (1) @2025-07-03T11:32:53.182796Z
[000.005] Server answered
[000.046] SSL/TLS is working correctly on this server
[000.047] <‑‑ 220 mx.google.com ESMTP 6a1803df08f44-702ac245251si54605326d6.443 - gsmtp
[000.047] We are allowed to connect
[000.047] ‑‑> EHLO www12-azure.checktls.com
[000.061] <‑‑ 250-mx.google.com at your service, [40.76.159.115]
250-SIZE 157286400
250-8BITMIME
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
[000.061] We can use this server
[000.061] TLS is an option on this server
[000.061] ‑‑> STARTTLS
[000.073] <‑‑ 220 2.0.0 Ready to start TLS
[000.073] STARTTLS command works on this server
[000.074] SSL_ocsp_mode = SSL_OCSP_FULL_CHAIN
[000.100] Connection converted to SSL/TLS
SSLVersion in use: TLSv1_3
Cipher in use: TLS_AES_256_GCM_SHA384
Perfect Forward Secrecy: yes
Session Algorithm in use: Curve X25519 DHE(253 bits)
Certificate #1 of 4 (sent by MX):
Cert VALIDATED: ok
Cert Hostname VERIFIED (smtp.google.com = mx.google.com | DNS:mx.google.com | DNS:smtp.google.com | DNS:aspmx.l.google.com | DNS:alt1.aspmx.l.google.com | DNS:alt2.aspmx.l.google.com | DNS:alt3.aspmx.l.google.com | DNS:alt4.aspmx.l.google.com | DNS:gmail-smtp-in.l.google.com | DNS:alt1.gmail-smtp-in.l.google.com | DNS:alt2.gmail-smtp-in.l.google.com | DNS:alt3.gmail-smtp-in.l.google.com | DNS:alt4.gmail-smtp-in.l.google.com | DNS:gmr-smtp-in.l.google.com | DNS:alt1.gmr-smtp-in.l.google.com | DNS:alt2.gmr-smtp-in.l.google.com | DNS:alt3.gmr-smtp-in.l.google.com | DNS:alt4.gmr-smtp-in.l.google.com | DNS:mx1.smtp.goog | DNS:mx2.smtp.goog | DNS:mx3.smtp.goog | DNS:mx4.smtp.goog | DNS:aspmx2.googlemail.com | DNS:aspmx3.googlemail.com | DNS:aspmx4.googlemail.com | DNS:aspmx5.googlemail.com | DNS:gmr-mx.google.com)
Not Valid Before: Jun 17 20:02:56 2025 GMT
Not Valid After: Sep 9 20:02:55 2025 GMT
Seconds Until Expired: 5905801
subject: /CN=mx.google.com
issuer: /C=US/O=Google Trust Services/CN=WR2
Certificate #2 of 4 (sent by MX):
Cert VALIDATED: ok
Not Valid Before: Dec 13 09:00:00 2023 GMT
Not Valid After: Feb 20 14:00:00 2029 GMT
Seconds Until Expired: 114748026
subject: /C=US/O=Google Trust Services/CN=WR2
issuer: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
Certificate #3 of 4 (added from CA Root Store):
Cert VALIDATED: ok
Not Valid Before: Jun 22 00:00:00 2016 GMT
Not Valid After: Jun 22 00:00:00 2036 GMT
Seconds Until Expired: 346163226
subject: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
issuer: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
Certificate #4 of 4 (sent by MX):
Cert VALIDATED:
Not Valid Before: Jun 19 00:00:42 2020 GMT
Not Valid After: Jan 28 00:00:42 2028 GMT
Seconds Until Expired: 81088068
subject: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
issuer: /C=BE/O=GlobalSign nv-sa/OU=Root CA/CN=GlobalSign Root CA
[000.261] > EHLO www12-azure.checktls.com
[000.273] < 250-mx.google.com at your service, [40.76.159.115]
250-SIZE 157286400
250-8BITMIME
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
[000.273] SSL/TLS is working correctly on this server
[000.273] > MAIL FROM:[email protected]
[000.286] < 250 2.1.0 OK 6a1803df08f44-702ac245251si54605326d6.443 - gsmtp
[000.286] Sender is OK
[000.286] > QUIT
[000.299] < 221 2.0.0 closing connection 6a1803df08f44-702ac245251si54605326d6.443 - gsmtp

seconds test stage and result
[000.000] Trying TLS on smtp.google.com[142.251.179.26:25] (1) @2025-07-03T11:32:53.484831Z
[000.005] Server answered
[000.030] SSL/TLS is working correctly on this server
[000.030] <‑‑ 220 mx.google.com ESMTP af79cd13be357-7d44328c0b6si1476676285a.541 - gsmtp
[000.030] We are allowed to connect
[000.030] ‑‑> EHLO www12-azure.checktls.com
[000.053] <‑‑ 250-mx.google.com at your service, [40.76.159.115]
250-SIZE 157286400
250-8BITMIME
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
[000.053] We can use this server
[000.053] TLS is an option on this server
[000.053] ‑‑> STARTTLS
[000.065] <‑‑ 220 2.0.0 Ready to start TLS
[000.065] STARTTLS command works on this server
[000.065] SSL_ocsp_mode = SSL_OCSP_FULL_CHAIN
[000.084] Connection converted to SSL/TLS
SSLVersion in use: TLSv1_3
Cipher in use: TLS_AES_256_GCM_SHA384
Perfect Forward Secrecy: yes
Session Algorithm in use: Curve X25519 DHE(253 bits)
Certificate #1 of 4 (sent by MX):
Cert VALIDATED: ok
Cert Hostname VERIFIED (smtp.google.com = mx.google.com | DNS:mx.google.com | DNS:smtp.google.com | DNS:aspmx.l.google.com | DNS:alt1.aspmx.l.google.com | DNS:alt2.aspmx.l.google.com | DNS:alt3.aspmx.l.google.com | DNS:alt4.aspmx.l.google.com | DNS:gmail-smtp-in.l.google.com | DNS:alt1.gmail-smtp-in.l.google.com | DNS:alt2.gmail-smtp-in.l.google.com | DNS:alt3.gmail-smtp-in.l.google.com | DNS:alt4.gmail-smtp-in.l.google.com | DNS:gmr-smtp-in.l.google.com | DNS:alt1.gmr-smtp-in.l.google.com | DNS:alt2.gmr-smtp-in.l.google.com | DNS:alt3.gmr-smtp-in.l.google.com | DNS:alt4.gmr-smtp-in.l.google.com | DNS:mx1.smtp.goog | DNS:mx2.smtp.goog | DNS:mx3.smtp.goog | DNS:mx4.smtp.goog | DNS:aspmx2.googlemail.com | DNS:aspmx3.googlemail.com | DNS:aspmx4.googlemail.com | DNS:aspmx5.googlemail.com | DNS:gmr-mx.google.com)
Not Valid Before: Jun 2 08:36:34 2025 GMT
Not Valid After: Aug 25 08:36:33 2025 GMT
Seconds Until Expired: 4568619
subject: /CN=mx.google.com
issuer: /C=US/O=Google Trust Services/CN=WR2
Certificate #2 of 4 (sent by MX):
Cert VALIDATED: ok
Not Valid Before: Dec 13 09:00:00 2023 GMT
Not Valid After: Feb 20 14:00:00 2029 GMT
Seconds Until Expired: 114748026
subject: /C=US/O=Google Trust Services/CN=WR2
issuer: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
Certificate #3 of 4 (added from CA Root Store):
Cert VALIDATED: ok
Not Valid Before: Jun 22 00:00:00 2016 GMT
Not Valid After: Jun 22 00:00:00 2036 GMT
Seconds Until Expired: 346163226
subject: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
issuer: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
Certificate #4 of 4 (sent by MX):
Cert VALIDATED:
Not Valid Before: Jun 19 00:00:42 2020 GMT
Not Valid After: Jan 28 00:00:42 2028 GMT
Seconds Until Expired: 81088068
subject: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
issuer: /C=BE/O=GlobalSign nv-sa/OU=Root CA/CN=GlobalSign Root CA
[000.382] > EHLO www12-azure.checktls.com
[000.394] < 250-mx.google.com at your service, [40.76.159.115]
250-SIZE 157286400
250-8BITMIME
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
[000.394] SSL/TLS is working correctly on this server
[000.394] > MAIL FROM:[email protected]
[000.406] < 250 2.1.0 OK af79cd13be357-7d44328c0b6si1476676285a.541 - gsmtp
[000.406] Sender is OK
[000.406] > QUIT
[000.419] < 221 2.0.0 closing connection af79cd13be357-7d44328c0b6si1476676285a.541 - gsmtp

seconds test stage and result
[000.000] Trying TLS on smtp.google.com[142.251.179.27:25] (1) @2025-07-03T11:32:53.906305Z
[000.005] Server answered
[000.017] SSL/TLS is working correctly on this server
[000.018] <‑‑ 220 mx.google.com ESMTP 6a1803df08f44-6fd7736921asi166867886d6.247 - gsmtp
[000.018] We are allowed to connect
[000.018] ‑‑> EHLO www12-azure.checktls.com
[000.033] <‑‑ 250-mx.google.com at your service, [40.76.159.115]
250-SIZE 157286400
250-8BITMIME
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
[000.034] We can use this server
[000.034] TLS is an option on this server
[000.034] ‑‑> STARTTLS
[000.046] <‑‑ 220 2.0.0 Ready to start TLS
[000.046] STARTTLS command works on this server
[000.046] SSL_ocsp_mode = SSL_OCSP_FULL_CHAIN
[000.064] Connection converted to SSL/TLS
SSLVersion in use: TLSv1_3
Cipher in use: TLS_AES_256_GCM_SHA384
Perfect Forward Secrecy: yes
Session Algorithm in use: Curve X25519 DHE(253 bits)
Certificate #1 of 4 (sent by MX):
Cert VALIDATED: ok
Cert Hostname VERIFIED (smtp.google.com = mx.google.com | DNS:mx.google.com | DNS:smtp.google.com | DNS:aspmx.l.google.com | DNS:alt1.aspmx.l.google.com | DNS:alt2.aspmx.l.google.com | DNS:alt3.aspmx.l.google.com | DNS:alt4.aspmx.l.google.com | DNS:gmail-smtp-in.l.google.com | DNS:alt1.gmail-smtp-in.l.google.com | DNS:alt2.gmail-smtp-in.l.google.com | DNS:alt3.gmail-smtp-in.l.google.com | DNS:alt4.gmail-smtp-in.l.google.com | DNS:gmr-smtp-in.l.google.com | DNS:alt1.gmr-smtp-in.l.google.com | DNS:alt2.gmr-smtp-in.l.google.com | DNS:alt3.gmr-smtp-in.l.google.com | DNS:alt4.gmr-smtp-in.l.google.com | DNS:mx1.smtp.goog | DNS:mx2.smtp.goog | DNS:mx3.smtp.goog | DNS:mx4.smtp.goog | DNS:aspmx2.googlemail.com | DNS:aspmx3.googlemail.com | DNS:aspmx4.googlemail.com | DNS:aspmx5.googlemail.com | DNS:gmr-mx.google.com)
Not Valid Before: Jun 2 08:36:34 2025 GMT
Not Valid After: Aug 25 08:36:33 2025 GMT
Seconds Until Expired: 4568618
subject: /CN=mx.google.com
issuer: /C=US/O=Google Trust Services/CN=WR2
Certificate #2 of 4 (sent by MX):
Cert VALIDATED: ok
Not Valid Before: Dec 13 09:00:00 2023 GMT
Not Valid After: Feb 20 14:00:00 2029 GMT
Seconds Until Expired: 114748025
subject: /C=US/O=Google Trust Services/CN=WR2
issuer: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
Certificate #3 of 4 (added from CA Root Store):
Cert VALIDATED: ok
Not Valid Before: Jun 22 00:00:00 2016 GMT
Not Valid After: Jun 22 00:00:00 2036 GMT
Seconds Until Expired: 346163225
subject: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
issuer: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
Certificate #4 of 4 (sent by MX):
Cert VALIDATED:
Not Valid Before: Jun 19 00:00:42 2020 GMT
Not Valid After: Jan 28 00:00:42 2028 GMT
Seconds Until Expired: 81088067
subject: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
issuer: /C=BE/O=GlobalSign nv-sa/OU=Root CA/CN=GlobalSign Root CA
[000.159] > EHLO www12-azure.checktls.com
[000.172] < 250-mx.google.com at your service, [40.76.159.115]
250-SIZE 157286400
250-8BITMIME
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
[000.172] SSL/TLS is working correctly on this server
[000.172] > MAIL FROM:[email protected]
[000.184] < 250 2.1.0 OK 6a1803df08f44-6fd7736921asi166867886d6.247 - gsmtp
[000.184] Sender is OK
[000.184] > QUIT
[000.197] < 221 2.0.0 closing connection 6a1803df08f44-6fd7736921asi166867886d6.247 - gsmtp

seconds test stage and result
[000.000] Trying TLS on smtp.google.com[172.253.62.26:25] (1) @2025-07-03T11:32:54.105748Z
[000.005] Server answered
[000.017] SSL/TLS is working correctly on this server
[000.017] <‑‑ 220 mx.google.com ESMTP af79cd13be357-7d44329790esi1447013385a.566 - gsmtp
[000.017] We are allowed to connect
[000.017] ‑‑> EHLO www12-azure.checktls.com
[000.031] <‑‑ 250-mx.google.com at your service, [40.76.159.115]
250-SIZE 157286400
250-8BITMIME
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
[000.031] We can use this server
[000.031] TLS is an option on this server
[000.031] ‑‑> STARTTLS
[000.042] <‑‑ 220 2.0.0 Ready to start TLS
[000.042] STARTTLS command works on this server
[000.042] SSL_ocsp_mode = SSL_OCSP_FULL_CHAIN
[000.059] Connection converted to SSL/TLS
SSLVersion in use: TLSv1_3
Cipher in use: TLS_AES_256_GCM_SHA384
Perfect Forward Secrecy: yes
Session Algorithm in use: Curve X25519 DHE(253 bits)
Certificate #1 of 4 (sent by MX):
Cert VALIDATED: ok
Cert Hostname VERIFIED (smtp.google.com = mx.google.com | DNS:mx.google.com | DNS:smtp.google.com | DNS:aspmx.l.google.com | DNS:alt1.aspmx.l.google.com | DNS:alt2.aspmx.l.google.com | DNS:alt3.aspmx.l.google.com | DNS:alt4.aspmx.l.google.com | DNS:gmail-smtp-in.l.google.com | DNS:alt1.gmail-smtp-in.l.google.com | DNS:alt2.gmail-smtp-in.l.google.com | DNS:alt3.gmail-smtp-in.l.google.com | DNS:alt4.gmail-smtp-in.l.google.com | DNS:gmr-smtp-in.l.google.com | DNS:alt1.gmr-smtp-in.l.google.com | DNS:alt2.gmr-smtp-in.l.google.com | DNS:alt3.gmr-smtp-in.l.google.com | DNS:alt4.gmr-smtp-in.l.google.com | DNS:mx1.smtp.goog | DNS:mx2.smtp.goog | DNS:mx3.smtp.goog | DNS:mx4.smtp.goog | DNS:aspmx2.googlemail.com | DNS:aspmx3.googlemail.com | DNS:aspmx4.googlemail.com | DNS:aspmx5.googlemail.com | DNS:gmr-mx.google.com)
Not Valid Before: Jun 2 08:36:34 2025 GMT
Not Valid After: Aug 25 08:36:33 2025 GMT
Seconds Until Expired: 4568618
subject: /CN=mx.google.com
issuer: /C=US/O=Google Trust Services/CN=WR2
Certificate #2 of 4 (sent by MX):
Cert VALIDATED: ok
Not Valid Before: Dec 13 09:00:00 2023 GMT
Not Valid After: Feb 20 14:00:00 2029 GMT
Seconds Until Expired: 114748025
subject: /C=US/O=Google Trust Services/CN=WR2
issuer: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
Certificate #3 of 4 (added from CA Root Store):
Cert VALIDATED: ok
Not Valid Before: Jun 22 00:00:00 2016 GMT
Not Valid After: Jun 22 00:00:00 2036 GMT
Seconds Until Expired: 346163225
subject: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
issuer: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
Certificate #4 of 4 (sent by MX):
Cert VALIDATED:
Not Valid Before: Jun 19 00:00:42 2020 GMT
Not Valid After: Jan 28 00:00:42 2028 GMT
Seconds Until Expired: 81088067
subject: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
issuer: /C=BE/O=GlobalSign nv-sa/OU=Root CA/CN=GlobalSign Root CA
[000.414] > EHLO www12-azure.checktls.com
[000.425] < 250-mx.google.com at your service, [40.76.159.115]
250-SIZE 157286400
250-8BITMIME
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
[000.425] SSL/TLS is working correctly on this server
[000.425] > MAIL FROM:[email protected]
[000.436] < 250 2.1.0 OK af79cd13be357-7d44329790esi1447013385a.566 - gsmtp
[000.436] Sender is OK
[000.436] > QUIT
[000.450] < 221 2.0.0 closing connection af79cd13be357-7d44329790esi1447013385a.566 - gsmtp

seconds test stage and result
[000.000] Trying TLS on smtp.google.com[172.253.62.27:25] (1) @2025-07-03T11:32:54.558397Z
[000.004] Server answered
[000.017] SSL/TLS is working correctly on this server
[000.017] <‑‑ 220 mx.google.com ESMTP d75a77b69052e-4a7fc5620f7si159376481cf.565 - gsmtp
[000.017] We are allowed to connect
[000.017] ‑‑> EHLO www12-azure.checktls.com
[000.032] <‑‑ 250-mx.google.com at your service, [40.76.159.115]
250-SIZE 157286400
250-8BITMIME
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
[000.032] We can use this server
[000.032] TLS is an option on this server
[000.032] ‑‑> STARTTLS
[000.043] <‑‑ 220 2.0.0 Ready to start TLS
[000.044] STARTTLS command works on this server
[000.044] SSL_ocsp_mode = SSL_OCSP_FULL_CHAIN
[000.066] Connection converted to SSL/TLS
SSLVersion in use: TLSv1_3
Cipher in use: TLS_AES_256_GCM_SHA384
Perfect Forward Secrecy: yes
Session Algorithm in use: Curve X25519 DHE(253 bits)
Certificate #1 of 4 (sent by MX):
Cert VALIDATED: ok
Cert Hostname VERIFIED (smtp.google.com = mx.google.com | DNS:mx.google.com | DNS:smtp.google.com | DNS:aspmx.l.google.com | DNS:alt1.aspmx.l.google.com | DNS:alt2.aspmx.l.google.com | DNS:alt3.aspmx.l.google.com | DNS:alt4.aspmx.l.google.com | DNS:gmail-smtp-in.l.google.com | DNS:alt1.gmail-smtp-in.l.google.com | DNS:alt2.gmail-smtp-in.l.google.com | DNS:alt3.gmail-smtp-in.l.google.com | DNS:alt4.gmail-smtp-in.l.google.com | DNS:gmr-smtp-in.l.google.com | DNS:alt1.gmr-smtp-in.l.google.com | DNS:alt2.gmr-smtp-in.l.google.com | DNS:alt3.gmr-smtp-in.l.google.com | DNS:alt4.gmr-smtp-in.l.google.com | DNS:mx1.smtp.goog | DNS:mx2.smtp.goog | DNS:mx3.smtp.goog | DNS:mx4.smtp.goog | DNS:aspmx2.googlemail.com | DNS:aspmx3.googlemail.com | DNS:aspmx4.googlemail.com | DNS:aspmx5.googlemail.com | DNS:gmr-mx.google.com)
Not Valid Before: Jun 2 08:36:34 2025 GMT
Not Valid After: Aug 25 08:36:33 2025 GMT
Seconds Until Expired: 4568618
subject: /CN=mx.google.com
issuer: /C=US/O=Google Trust Services/CN=WR2
Certificate #2 of 4 (sent by MX):
Cert VALIDATED: ok
Not Valid Before: Dec 13 09:00:00 2023 GMT
Not Valid After: Feb 20 14:00:00 2029 GMT
Seconds Until Expired: 114748025
subject: /C=US/O=Google Trust Services/CN=WR2
issuer: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
Certificate #3 of 4 (added from CA Root Store):
Cert VALIDATED: ok
Not Valid Before: Jun 22 00:00:00 2016 GMT
Not Valid After: Jun 22 00:00:00 2036 GMT
Seconds Until Expired: 346163225
subject: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
issuer: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
Certificate #4 of 4 (sent by MX):
Cert VALIDATED:
Not Valid Before: Jun 19 00:00:42 2020 GMT
Not Valid After: Jan 28 00:00:42 2028 GMT
Seconds Until Expired: 81088067
subject: /C=US/O=Google Trust Services LLC/CN=GTS Root R1
issuer: /C=BE/O=GlobalSign nv-sa/OU=Root CA/CN=GlobalSign Root CA
[000.155] > EHLO www12-azure.checktls.com
[000.166] < 250-mx.google.com at your service, [40.76.159.115]
250-SIZE 157286400
250-8BITMIME
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
[000.166] SSL/TLS is working correctly on this server
[000.166] > MAIL FROM:[email protected]
[000.177] < 250 2.1.0 OK d75a77b69052e-4a7fc5620f7si159376481cf.565 - gsmtp
[000.177] Sender is OK
[000.177] > QUIT
[000.189] < 221 2.0.0 closing connection d75a77b69052e-4a7fc5620f7si159376481cf.565 - gsmtp

2

Based on your error messages showing “Connection timed out” to smtp.gmail.com:587, this is a classic case of port blocking by your hosting provider or ISP.

Root Cause Analysis

Your CheckTLS tests passed because they test inbound connections, but your issue is with outbound connections on port 587. The “Connection timed out” error indicates your server cannot establish an outbound connection to Google’s SMTP servers.

Immediate Solutions

  1. Check Port 587 Connectivity

Test if port 587 is blocked

telnet smtp.gmail.com 587

Alternative test

nc -zv smtp.gmail.com 587

Check with curl

curl -v telnet://smtp.gmail.com:587

  1. Contact Your Hosting Provider
    Many cloud providers (AWS, Azure, DigitalOcean, etc.) block outbound port 25 and sometimes 587 by default. You need to:
  • Request them to unblock port 587
  • Or use their recommended SMTP relay service

Debugging Commands

Check mail logs

sudo tail -f /var/log/maillog

Test email sending

echo “Test email” | mail -s “Test” [email protected]

Check Postfix queue

sudo postqueue -p

Flush mail queue after fixing

sudo postfix flush

Most Likely Solution

Given your symptoms, your hosting provider is blocking port 587. Contact them to:

  1. Unblock port 587 for outbound connections
  2. Get their recommended SMTP relay service
  3. Check if they have specific requirements for sending email

Many providers require you to use their SMTP relay to prevent spam. This is especially common with cloud VPS providers.

Would you mind sharing which hosting provider you’re using? This would help provide more specific guidance.