Sent emails do not reach their destination (gmail) [SOLVED]

Hello!

I installed ISPConfig and created two mailboxes. I can log in through Roundcube Webmail and send and receive messages internally.

However, the messages I send externally don't arrive.

Example: I receive messages from Gmail, but the ones I send to Gmail never arrive.

This is the log from /var/log/mail.log after I send an email through roundcube:

Code:

2025-08-22T21:44:02.088078-03:00 server1 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=::1, lip=::1, mpid=13843, secured, session=<+gxlnv08Uq8AAAAAAAAAAAAAAAAAAAAB>
2025-08-22T21:44:02.097384-03:00 server1 dovecot: imap([email protected])<13843><+gxlnv08Uq8AAAAAAAAAAAAAAAAAAAAB>: Disconnected: Logged out in=32 out=549 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0
2025-08-22T21:44:02.153764-03:00 server1 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=::1, lip=::1, mpid=13845, secured, session=<rhBmnv08Wq8AAAAAAAAAAAAAAAAAAAAB>
2025-08-22T21:44:02.169335-03:00 server1 dovecot: imap([email protected])<13845><rhBmnv08Wq8AAAAAAAAAAAAAAAAAAAAB>: Disconnected: Logged out in=44 out=656 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0
2025-08-22T21:44:11.426779-03:00 server1 postfix/smtpd[13583]: connect from localhost[::1]
2025-08-22T21:44:11.427796-03:00 server1 postfix/smtpd[13583]: warning: connect to Milter service inet:localhost:11332: Connection refused
2025-08-22T21:44:11.439624-03:00 server1 postfix/smtpd[13583]: 6B46BC1B7D: client=localhost[::1], sasl_method=LOGIN, [email protected]
2025-08-22T21:44:11.481308-03:00 server1 postfix/cleanup[13605]: 6B46BC1B7D: message-id=<[email protected]>
2025-08-22T21:44:11.483980-03:00 server1 postfix/qmgr[11097]: 6B46BC1B7D: from=<[email protected]>, size=628, nrcpt=1 (queue active)
2025-08-22T21:44:11.486583-03:00 server1 postfix/smtpd[13583]: disconnect from localhost[::1] ehlo=1 auth=1 mail=1 rcpt=1 data=1 quit=1 commands=6
2025-08-22T21:44:11.517346-03:00 server1 postfix/smtp[13846]: warning: DNSSEC validation may be unavailable
2025-08-22T21:44:11.518163-03:00 server1 postfix/smtp[13846]: warning: reason: dnssec_probe 'ns:.' received a response that is not DNSSEC validated
2025-08-22T21:44:11.522098-03:00 server1 postfix/smtp[13846]: connect to gmail-smtp-in.l.google.com[2800:3f0:4003:c02::1a]:25: Network is unreachable
2025-08-22T21:44:11.524779-03:00 server1 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=::1, lip=::1, mpid=13848, secured, session=<oOb0nv08XOAAAAAAAAAAAAAAAAAAAAAB>
2025-08-22T21:44:11.538328-03:00 server1 dovecot: imap([email protected])<13848><oOb0nv08XOAAAAAAAAAAAAAAAAAAAAAB>: Disconnected: Logged out in=440 out=713 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0
2025-08-22T21:44:12.149724-03:00 server1 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=::1, lip=::1, mpid=13850, secured, session=<+JX+nv08auAAAAAAAAAAAAAAAAAAAAAB>
2025-08-22T21:44:12.170609-03:00 server1 dovecot: imap([email protected])<13850><+JX+nv08auAAAAAAAAAAAAAAAAAAAAAB>: Disconnected: Logged out in=70 out=770 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0
2025-08-22T21:44:12.380763-03:00 server1 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=::1, lip=::1, mpid=13853, secured, session=<NvMBn/08SLsAAAAAAAAAAAAAAAAAAAAB>
2025-08-22T21:44:12.396348-03:00 server1 dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=::1, lip=::1, mpid=13854, secured, session=<JCwCn/08ULsAAAAAAAAAAAAAAAAAAAAB>
2025-08-22T21:44:12.407619-03:00 server1 dovecot: imap([email protected])<13853><NvMBn/08SLsAAAAAAAAAAAAAAAAAAAAB>: Disconnected: Logged out in=318 out=3847 deleted=0 expunged=0 trashed=0 hdr_count=6 hdr_bytes=1321 body_count=0 body_bytes=0
2025-08-22T21:44:12.410734-03:00 server1 dovecot: imap([email protected])<13854><JCwCn/08ULsAAAAAAAAAAAAAAAAAAAAB>: Disconnected: Logged out in=120 out=846 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0
2025-08-22T21:44:13.415923-03:00 server1 postfix/smtp[13796]: connect to gmail-smtp-in.l.google.com[142.251.0.26]:25: Connection timed out
2025-08-22T21:44:13.416362-03:00 server1 postfix/smtp[13796]: connect to gmail-smtp-in.l.google.com[2800:3f0:4003:c03::1a]:25: Network is unreachable

 

Easier said than done if you're hosting at home.
Here in NL almost all (at least the major) ISP's block port 25 to anywhere else outside of their own network (and often inbound too) on consumer connections. Only (the more expensive) business connections allow it.
So you'll need to use your ISP's smtp server or some (mostly paid and limited) relay service as smarthost.

 

Hello, everyone!

First of all, thank you very much for your help!

Here's what I had to do to be able to send emails:

1. I had to get an email account from my provider.

For example: [email protected]

2. I had to point DNS MX records to my provider:

MX mx mx-vip-02.xxx.net auto 5
MX mx mx-vip-01.xxx.net auto 5

3. I had to edit the /etc/postfix/main.cf file as shown in the example below:

Code:

relayhost = [smtp.xxx.net]:587
smtp_use_tls = yes
smtp_tls_security_level = may
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_sasl_tls_security_options = noanonymous

4. I had to create the file /etc/postfix/sasl_passwd with my login data:

Code:

[smtp.xxx.net]:587 [email protected]:Pa$$word

5. I had to create the Postfix lookup table by running:

postmap /etc/postfix/sasl_passwd

6. Set the correct permissions by running:

chmod 600 /etc/postfix/sasl_passwd /etc/postfix/sasl_passwd.db

7. Restart Postfix by running:

systemctl restart postfix

8. Open a terminal and observe:

tail -f /var/log/mail.log

9. Open another terminal and test:

echo "Test sending via Postfix" | mail -s "Postfix Test" [email protected]

---

After these steps, my sent emails started arriving in Gmail.

Any tips on what to do next?

I have little experience with email servers. Your help is welcome!

 

In your original post you didn't say if you could receive external mail.
You only mention sending and receiving internally.

With the changes you've made now all external mail will be received in your new mail account at your provider (the same account as you're using as smarthost to send mail).
Next step is to configure fetchmail in your ispconfig I would say, to download externally received mail at your provider into your ispconfig mailbox.

 

It is now possible to send emails externally.
And receive external emails in your own mailboxes. They don't appear in my provider's account, only in the ones created in ISPConfig.

I'm not sure if it's necessary to configure Fetchmail... since I can see incoming emails through Roundcube.

 

No you don't have to if mail is received correctly.

I assumed mail would be received by your provider's malbox since you changed the mx records.
But apparently those mx records point to your ispconfig server then.

 

That's nifty. If they're not charging it's even better. Letting someone else do DNS is less trauma inducing.