실시된 문제 해결 단계 요약:
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공식 Docker 설치 가이드를 사용하여 Spaceship VPS(미국 피닉스)에 Discourse를 설치했습니다.
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SSH 명령을 통해 관리자 계정을 생성했습니다.
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Spacemail을 사용하여 SMTP를 설정했습니다 (mail.spacemail.com, 포트 465, SSL, 전체 이메일 주소를 사용자 이름으로 사용, 올바른 비밀번호).
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SMTP 비밀번호를 여러 번 초기화하고 다시 입력했습니다.
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SMTP 서버로 mail.spacemail.com과 smtp.spacemail.com을 모두 시도했습니다.
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Spacemail 지원팀과 확인한 결과, 상대방 측에는 제한이나 차단이 없음을 확인했습니다.
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모든 DNS 레코드(MX, SPF, DKIM)가 정확하고 전파되었는지 확인했습니다.
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같은 Spacemail 계정으로 Gmail에서 이메일을 성공적으로 보내고 받을 수 있었습니다 (Discourse 외부에서는 SMTP가 정상 작동함).
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VPS에서 telnet과 openssl을 사용하여 SMTP 연결을 테스트했습니다 (TLS 핸드셰이크와 SMTP 배너를 성공적으로 수신함).
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Docker 네트워크 MTU를 1400으로 변경하고 Docker와 Discourse 컨테이너를 재시작했습니다.
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컨테이너 내에서 Redis, PostgreSQL 및 기타 모든 서비스가 올바르게 실행 중인지 확인했습니다.
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각 변경 사항 후 Discourse 앱의 destroy/start 및 전체 재빌드를 모두 시도했습니다.
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로그를 확인한 결과: 이메일 전송 시 Net::ReadTimeout 오류만 발생하고, 다른 오류는 없었습니다.
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Discourse 관리자 인터페이스에서 “SMTP 사용”이 활성화되어 있는지 확인했습니다.
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이 문제를 해결하기 위해 Spaceship/Spacemail 지원팀과 라이브 채팅으로 며칠 동안 약 7시간을 보냈습니다.
이 모든 단계를 거쳤음에도 Discourse는 여전히 이메일을 보내지 못하고 항상 Net::ReadTimeout 오류를 반환합니다.
root@ubuntu-2vcpu-amd-2gb-us-7yr03:/var/discourse# telnet ``mail.spacemail.com`` 465Trying 198.177.121.32…Connected to ``mail.spacemail.com``.Escape character is ‘^]’.
(app.yml) ENV:
env:LC_ALL: en_US.UTF-8LANG: en_US.UTF-8LANGUAGE: en_US.UTF-8
DISCOURSE_DEFAULT_LOCALE: en
UNICORN_WORKERS: 4
DISCOURSE_HOSTNAME: citygaming.icu
DISCOURSE_DEVELOPER_EMAILS: ‘info@citygaming.icu’
DISCOURSE_SMTP_ADDRESS: mail.spacemail.com
DISCOURSE_SMTP_PORT: 465
DISCOURSE_SMTP_USER_NAME: info@citygaming.icu
DISCOURSE_SMTP_PASSWORD: “” –> 특수 문자를 사용 중입니다
DISCOURSE_SMTP_ENABLE_START_TLS: false
DISCOURSE_SMTP_SSL: true
DISCOURSE_SMTP_DOMAIN: citygaming.icu
DISCOURSE_NOTIFICATION_EMAIL: forum@citygaming.icu
root@ubuntu-2vcpu-amd-2gb-us-7yr03:/var/discourse# openssl s_client -connect mail.spacemail.com:465
CONNECTED(00000003)
depth=2 C = GB, O = Sectigo Limited, CN = Sectigo Public Server Authentication Root R46
verify return:1
depth=1 C = GB, O = Sectigo Limited, CN = Sectigo Public Server Authentication CA DV R36
verify return:1
depth=0 CN = *.spacemail.com
verify return:1
---
Certificate chain
0 s:CN = *.spacemail.com
i:C = GB, O = Sectigo Limited, CN = Sectigo Public Server Authentication CA DV R36
a:PKEY: rsaEncryption, 2048 (bit); sigalg: RSA-SHA384
v:NotBefore: Jun 11 00:00:00 2025 GMT; NotAfter: Jun 27 23:59:59 2026 GMT
1 s:C = GB, O = Sectigo Limited, CN = Sectigo Public Server Authentication CA DV R36
i:C = GB, O = Sectigo Limited, CN = Sectigo Public Server Authentication Root R46
a:PKEY: rsaEncryption, 3072 (bit); sigalg: RSA-SHA384
v:NotBefore: Mar 22 00:00:00 2021 GMT; NotAfter: Mar 21 23:59:59 2036 GMT
2 s:C = GB, O = Sectigo Limited, CN = Sectigo Public Server Authentication Root R46
i:C = US, ST = New Jersey, L = Jersey City, O = The USERTRUST Network, CN = USERTrust RSA Certification Authority
a:PKEY: rsaEncryption, 4096 (bit); sigalg: RSA-SHA384
v:NotBefore: Mar 22 00:00:00 2021 GMT; NotAfter: Jan 18 23:59:59 2038 GMT
3 s:C = US, ST = New Jersey, L = Jersey City, O = The USERTRUST Network, CN = USERTrust RSA Certification Authority
i:C = US, ST = New Jersey, L = Jersey City, O = The USERTRUST Network, CN = USERTrust RSA Certification Authority
a:PKEY: rsaEncryption, 4096 (bit); sigalg: RSA-SHA384
v:NotBefore: Feb 1 00:00:00 2010 GMT; NotAfter: Jan 18 23:59:59 2038 GMT
---
Server certificate
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
subject=CN = *.spacemail.com
issuer=C = GB, O = Sectigo Limited, CN = Sectigo Public Server Authentication CA DV R36
---
No client certificate CA names sent
Peer signing digest: SHA256
Peer signature type: RSA-PSS
Server Temp Key: X25519, 253 bits
---
SSL handshake has read 7057 bytes and written 400 bytes
Verification: OK
---
New, TLSv1.3, Cipher is TLS_AES_256_GCM_SHA384
Server public key is 2048 bit
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
Early data was not sent
Verify return code: 0 (ok)
---
---
Post-Handshake New Session Ticket arrived:
SSL-Session:
Protocol : TLSv1.3
Cipher : TLS_AES_256_GCM_SHA384
Session-ID: 8FACA20AB7071487B74738E7FA28813C1CA106651D80EB46D271486C67E4432B
Session-ID-ctx:
Resumption PSK: F99B4B27314220CB53DEE7B1D852B2AE360D39472E1F020806FAC5D40A72F206636EA0B50545C9F1875BCACB5FD35F07
PSK identity: None
PSK identity hint: None
SRP username: None
TLS session ticket lifetime hint: 7200 (seconds)
TLS session ticket:
0000 - 23 bd a5 51 88 3e 2e 7f-eb 8d 81 00 95 7a a7 8b #..Q.>.......z..
0010 - ce 97 c1 5e 12 02 2a 46-de d9 96 d7 06 f0 b1 47 ...^..*F.......G
0020 - 1d 79 69 7f 8e 9d f4 4a-6a cb ec 00 42 70 d6 6b .yi....Jj...Bp.k
0030 - a1 37 1b 9d 61 47 4a e1-16 13 bc bb e7 ee f8 de .7..aGJ.........
0040 - 26 fb c1 00 b0 15 76 f0-80 a3 14 8b 10 f2 c7 ab &.....v.........
0050 - 5c 54 cb b3 16 e2 d2 ab-36 97 c9 82 14 1d 45 d4 \T......6.....E.
0060 - d7 4d c0 fc 9e 77 e3 44-c8 87 16 13 3a 1f c2 02 .M...w.D....:...
0070 - 65 03 51 14 bf ab d0 0e-51 e5 9e 95 07 ef 33 f5 e.Q.....Q.....3.
0080 - 48 9c 89 8e d9 8e 1f ea-38 3a 21 2a c1 64 44 a8 H.......8:!*.dD.
0090 - b2 9a 69 f2 ca fa 9e 57-12 14 36 32 fb 40 b1 06 ..i....W..62.@..
00a0 - 9e a4 b8 21 19 90 65 f8-6d ce 2d 6f 53 e0 72 23 ...!..e.m.-oS.r#
00b0 - 5b ca b8 f8 79 bd 07 9e-97 95 d4 d3 d5 f6 25 93 [...y.........%.
00c0 - 33 02 71 1d 55 be 9c d3-14 32 bb 9b 4e 65 67 78 3.q.U....2..Negx
Start Time: 1758479949
Timeout : 7200 (sec)
Verify return code: 0 (ok)
Extended master secret: no
Max Early Data: 0
---
read R BLOCK
220 SpaceMail.com Mail Node