My SMTP credentials don't work

[iamjohnseun]

I have installed Postal as a Docker container on my Ubuntu VPS and everything runs smoothly, i set up my DNS records and rDNS(PTR) and all seems good. I can send emails from the Postal web interface although i am unable to access the web interface through HTTPS even after installing caddy.
My problem is, after generating credentials, my mail client is unable to authenticate with my server and send a message.
I get credentials that look like this:

host: mail.example.com
username: organization/username
password: randomGeneratedPassword
port: 25

My SMTP logs looks like this at the moment:
smtp_1 | [9] [2021-11-10T14:54:44.288] INFO -- : Listening on :::25
smtp_1 | [9] [2021-11-10T16:47:00.839] DEBUG -- : [C4GEDZ] Connection opened from ::ffff:8.8.8.8
smtp_1 | [9] [2021-11-10T16:47:00.839] DEBUG -- : [C4GEDZ] Client identified as ::ffff:8.8.8.8
smtp_1 | [9] [2021-11-10T16:47:00.875] DEBUG -- : [C4GEDZ] <= EHLO eu-lon-85.sample.com
smtp_1 | [9] [2021-11-10T16:47:00.892] DEBUG -- : [C4GEDZ] => 250-My capabilities are
smtp_1 | [9] [2021-11-10T16:47:00.893] DEBUG -- : [C4GEDZ] => 250 AUTH CRAM-MD5 PLAIN LOGIN
smtp_1 | [9] [2021-11-10T16:47:00.967] DEBUG -- : [C4GEDZ] <= MAIL FROM:<[email protected]>
smtp_1 | [9] [2021-11-10T16:47:00.967] DEBUG -- : [C4GEDZ] => 250 OK
smtp_1 | [9] [2021-11-10T16:47:00.984] DEBUG -- : [C4GEDZ] <= RCPT TO:<[email protected]>
smtp_1 | [9] [2021-11-10T16:47:01.436] DEBUG -- : [C4GEDZ] => 530 Authentication required
smtp_1 | [9] [2021-11-10T16:47:06.454] DEBUG -- : [C4GEDZ] <= QUIT
smtp_1 | [9] [2021-11-10T16:47:06.454] DEBUG -- : [C4GEDZ] => 221 Closing Connection
smtp_1 | [9] [2021-11-10T16:47:06.454] DEBUG -- : [C4GEDZ] Connection closed

I have changed some details in the log, i hope it does not confuse anyone trying to help.
I have tried different combinations but to no luck, anyone that has successfully got this to work, kindly advice.

[willpower232]

i am unable to access the web interface though HTTPS even after installing caddy

my mail client is unable to authenticate with my server

what error messages do you have in both cases?

[iamjohnseun]

SMTP Authentication Errors. My initial thought is that i was not using the credentials right. Perhaps there is a right way to do it.
Could you please show me the documentation or video for Postal SMTP creedential usage. That shows how the SMTP credentials be used in a mail client.
The username provided by postal looks like
username: organization/username
And the password being the random generated. I am familiar with SMTP usernames being email addresses.

[willpower232]

I believe people use https://smtper.net/ to test, you should use the details exactly as they are shown on that page.

The results from smtper will confirm where any problems are.

[iamjohnseun]

Thank you so much for your replies. I will attempt to use https://smtper.net/ to test and provide feedback. Thank you once again.

[iamjohnseun]

I used https://smtper.net/ and i successfully received an email.

[willpower232]

so that means that wherever you are sending emails from may have it blocked.

[iamjohnseun]

I was sending from a client called "supermailer" and it did not authenticate with my server using the same details i entered in https://smtper.net. Now i just have to figure out why i cant get https on my web interface even though i installed caddy. Thank you and i appreciate all your help.

[iamjohnseun]

For anyone else that might need help with this,

• Use the details as generated by postal. You can get a sample credential by visiting subdomain.yourdomain.tld/org/saturn-mail-agent/servers/pan/help/outgoing
• You can test your server using https://smtper.net/
• Make sure your port is correct and you are not using a custom port. You can verify from your postal.yml file