# Email errors when using Jenkins only **URL:** \ **Category:** Using Jenkins\ **Tags:** question\ **Created:** [September 22, 2025, 8:27am UTC](https://community.jenkins.io/t/email-errors-when-using-jenkins-only/35631 "2025-09-22T08:27:33Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Machiel](https://avatars.discourse-cdn.com/v4/letter/m/f05b48/32.png) [@Machiel](https://community.jenkins.io/u/Machiel)\ **Post date:** [September 22, 2025, 8:27am UTC](https://community.jenkins.io/t/email-errors-when-using-jenkins-only/35631/1 "2025-09-22T08:27:33Z")
Good day, I hope this finds you well. I am fairly new to Jenkins I am struggling to figure out an issue with email needing to be sent by my script in Jenkins. The script need to perform a few tasks and then send an email to the user or set of users with the console output of the events. Everything seems to be working quite well besides the email portion. I am using the email extension plugin and have configured the mail to make use of the local postfix mail server which uses a smarthost for sending emails. when I select the test email option, it passes and I get the test email. When I send mails from local os scripts or other tests from the OS then the mails go through without any issues. However, when I try to send the email from the pipeline using the mailext option , it shows in the console that it is successful, however on postfix side I get the following error and mails are not received. `warning: TLS library problem: error:0A000416:SSL routines::sslv3 alert certificate unknown:../ssl/record/rec_layer_s3.c:1599:SSL alert number 46` This issue only seems to be happening when trying to send email via the pipeline using the mailext option (I need to attach the build logs to the mail). Does anybody perhaps know what I can look at to get this resolved ? I have tried using the letsencrypt certificates as well, however as this is configured for the nginx proxy, it breaks the mails completely. > **Jenkins setup:** > > ``` > Jenkins: 2.516.3 > OS: Linux - 6.8.0-83-generic > Java: 17.0.16 - Ubuntu (OpenJDK 64-Bit Server VM) > > analysis-model-api:13.8.0-902.v26f80296f743 > ant:518.v8d8dc7945eca\_ > antisamy-markup-formatter:173.v680e3a\_b\_69ff3 > apache-httpcomponents-client-4-api:4.5.14-269.vfa\_2321039a\_83 > apache-httpcomponents-client-5-api:5.5-166.v870a\_96374f91 > asm-api:9.8-163.vb\_2a\_96d3f9c3c > bootstrap5-api:5.3.8-876.vb\_c62a\_27d9a\_77 > bouncycastle-api:2.30.1.81-264.v95c79c0e772c > branch-api:2.1244.vf95c81f1641c > build-timeout:1.38 > caffeine-api:3.2.2-178.v353b\_8428ed56 > checks-api:373.vfe7645102093 > cloudbees-folder:6.1040.v8a\_e6330a\_54e3 > commons-lang3-api:3.18.0-98.v3a\_674c06072d > commons-text-api:1.14.0-194.v804a\_dc3a\_1b\_d8 > credentials:1447.v4cb\_b\_539b\_5321 > credentials-binding:702.vfe613e537e88 > dark-theme:574.va\_19f05d54df5 > data-tables-api:2.3.4-1400.vb\_1e3e3c4dfc8 > display-url-api:2.217.va\_6b\_de84cc74b\_ > durable-task:595.ve87b\_f1318d67 > echarts-api:6.0.0-1146.v5c8f3b\_8f0573 > eddsa-api:0.3.0.1-19.vc432d923e5ee > email-ext:1925.v1598902b\_58dd > emailext-template:233.v1eb\_88fc160b\_5 > font-awesome-api:7.0.1-859.v128d3a\_efb\_6e5 > forensics-api:3.1754.v2a\_6613b\_77002 > git:5.7.0 > git-client:6.4.0 > github:1.45.0 > github-api:1.330-492.v3941a\_032db\_2a\_ > github-branch-source:1864.v411feec5e78e > gradle:2.16.1149.v711b\_998b\_0532 > gson-api:2.13.2-173.va\_a\_092315913c > instance-identity:203.v15e81a\_1b\_7a\_38 > ionicons-api:94.vcc3065403257 > jackson2-api:2.20.0-411.v6ef8fdee4fe9 > jakarta-activation-api:2.1.3-2 > jakarta-mail-api:2.1.3-3 > javax-activation-api:1.2.0-8 > javax-mail-api:1.6.2-11 > jaxb:2.3.9-133.vb\_ec76a\_73f706 > jdk-tool:83.v417146707a\_3d > jjwt-api:0.11.5-120.v0268cf544b\_89 > joda-time-api:2.14.0-149.v1c3ce991d1b\_9 > jquery3-api:3.7.1-594.vb\_3864f326cf0 > json-api:20250517-173.v596efb\_962a\_31 > json-path-api:2.9.0-190.veefca\_05d5477 > jsoup:1.21.2-66.v6ea\_38164b\_8a\_2 > junit:1355.v45e2ea\_65863c > ldap:780.vcb\_33c9a\_e4332 > mailer:522.va\_995fa\_cfb\_8b\_d > matrix-auth:3.2.8 > matrix-project:858.vb\_b\_eb\_9a\_7ea\_99e > metrics:4.2.33-484.v2fcd689980d1 > mina-sshd-api-common:2.16.0-167.va\_269f38cc024 > mina-sshd-api-core:2.16.0-167.va\_269f38cc024 > okhttp-api:4.11.0-189.v976fa\_d3379d6 > pam-auth:1.12 > pipeline-build-step:571.v08a\_fffd4b\_0ce > pipeline-github-lib:65.v203688e7727e > pipeline-graph-view:642.v39f37c8e1e70 > pipeline-groovy-lib:752.vdddedf804e72 > pipeline-input-step:534.v352f0a\_e98918 > pipeline-milestone-step:138.v78ca\_76831a\_43 > pipeline-model-api:2.2273.v643f36ed9e94 > pipeline-model-definition:2.2273.v643f36ed9e94 > pipeline-model-extensions:2.2273.v643f36ed9e94 > pipeline-stage-step:322.vecffa\_99f371c > pipeline-stage-tags-metadata:2.2273.v643f36ed9e94 > plain-credentials:199.v9f8e1f741799 > plugin-util-api:6.1167.v022176c7e0ca\_ > prism-api:1.30.0-609.vf0a\_df102d9a\_f > resource-disposer:0.25 > role-strategy:799.v5b\_e7b\_ecc231e > scm-api:707.v749f968369d4 > script-security:1378.vf25626395f49 > snakeyaml-api:2.3-125.v4d77857a\_b\_402 > ssh-agent:386.v36cc0c7582f0 > ssh-credentials:361.vb\_f6760818e8c > ssh-slaves:3.1071.v0d059c7b\_c555 > sshd:3.374.v19b\_d59ce6610 > structs:353.v261ea\_40a\_80fb\_ > theme-manager:319.v9193461f9671 > timestamper:1.30 > token-macro:477.vd4f0dc3cb\_cf1 > trilead-api:2.209.v0e69b\_c43c245 > variant:70.va\_d9f17f859e0 > warnings-ng:12.9783.ve1cb\_9f060738 > workflow-aggregator:608.v67378e9d3db\_1 > workflow-api:1384.vdc05a\_48f535f > workflow-basic-steps:1079.vce64b\_a\_929c5a\_ > workflow-cps:4183.v94b\_6fd39da\_c1 > workflow-durable-task-step:1464.v2d3f5c68f84c > workflow-job:1546.v62a\_c59c112dd > workflow-multibranch:821.vc3b\_4ea\_780798 > workflow-scm-step:452.vdf1ca\_c8d3a\_87 > workflow-step-api:706.v518c5dcb\_24c0 > workflow-support:989.va\_20a\_1a\_57710a\_ > ws-cleanup:0.49 > ``` ---
**Author:** ![poddingue](https://dub1.discourse-cdn.com/flex013/user_avatar/community.jenkins.io/poddingue/32/985_2.png) [@poddingue](https://community.jenkins.io/u/poddingue)\ **Post date:** [September 22, 2025, 9:06am UTC](https://community.jenkins.io/t/email-errors-when-using-jenkins-only/35631/2 "2025-09-22T09:06:11Z")
Hello and welcome to this community, @Machiel! 👋 It looks like the issue boils down to a TLS/SSL trust problem between Jenkins (running on Java) and your Postfix smarthost. The interesting bit is that the **test email works** , but pipeline emails fail, and I guess that’s because the pipeline goes through [JavaMail](https://javaee.github.io/javamail/) (via the [Email Extension plugin](https://plugins.jenkins.io/email-ext/)), which is stricter about certificates. Here are a few things you might try: **1. Make sure Jenkins’ Java trusts the certificate** - If your smarthost uses a self-signed cert or an internal CA, Java won’t accept it out of the box. - You’ll need to import the CA cert into the Java truststore Jenkins is using. For example: ```auto keytool -import -alias mysmarthost \ -keystore $JAVA_HOME/lib/security/cacerts \ -file /path/to/ca.crt ``` (default password is `changeit`) Then restart Jenkins so it picks up the change. **2. Double-check your Email Extension plugin settings** - Make sure SMTP host/port/TLS options match exactly what works at the OS level. - If your smarthost expects **STARTTLS** , uncheck “Use SSL” and enable “Use TLS” instead. **3. Look at your pipeline config** A minimal example would be: ```auto emailext( subject: "Build log", body: "See attached log.", to: "user@example.com", attachLog: true ) ``` **4. If you’re using Let’s Encrypt** - Grab the full certificate chain and make sure the root CA is present in the Java truststore. Sometimes Java needs a little help recognizing the whole chain. * * * In short: it’s almost always a **missing CA cert** in the Java truststore. Once you import the right CA and restart Jenkins, your pipeline emails should work just like the test emails. Here’s a small **diagnostic pipeline snippet** you should be able to drop into a freestyle or multibranch pipeline to check whether Jenkins (via JavaMail) can actually connect to your SMTP server before a “real” email step runs: ```auto pipeline { agent any stages { stage('Check SMTP') { steps { script { try { // Try to send a minimal test email emailext( subject: "Jenkins SMTP test", body: "This is a test email sent from Jenkins pipeline at ${new Date()}", to: "your.email@example.com" ) echo "✅ SMTP test email sent successfully." } catch (err) { echo "❌ Failed to send SMTP test email." echo "Error: ${err}" error("SMTP connectivity or trust issue detected.") } } } } } } ``` What this gives you: - If the email succeeds → you’ll see the “✅ SMTP test email sent successfully.” message. - If it fails → you’ll see the full JavaMail error in the build log, which helps confirm whether it’s a **truststore/certificate** issue or something else (wrong TLS/port/credentials). ---
**Author:** ![Machiel](https://avatars.discourse-cdn.com/v4/letter/m/f05b48/32.png) [@Machiel](https://community.jenkins.io/u/Machiel)\ **Post date:** [September 22, 2025, 10:18am UTC](https://community.jenkins.io/t/email-errors-when-using-jenkins-only/35631/3 "2025-09-22T10:18:41Z")
Thank you very much for the suggestions. I tried the setup at first but this still did not work. I figured it must be because it is a self signed cert, so I used the letsencrypt certificate instead and also configured postfix. Then when testing with tls option enabled, I got an error on test email : java.security.cert.CertificateException: No subject alternative DNS name matching localhost found the certificate was for the fqdn so was strange to have received this, then eventually realized I specified localhost as my mail server. Added an /etc/hosts entry for localhost aliasing it to the fqdn locally and then it was happy again. Tested email via pipeline and this is now working , thank you. ---
**Author:** ![poddingue](https://dub1.discourse-cdn.com/flex013/user_avatar/community.jenkins.io/poddingue/32/985_2.png) [@poddingue](https://community.jenkins.io/u/poddingue)\ **Post date:** [September 22, 2025, 11:50am UTC](https://community.jenkins.io/t/email-errors-when-using-jenkins-only/35631/4 "2025-09-22T11:50:20Z")
Well done! 👏 Thanks a lot for the feedback. 🙏