Some mail servers (MX hosts) have associated TLSA records with certificate usage 2 (DANE-TA) and only match the currently active Let's Encrypt issuer CA ("X3"). The X3 certificate is soon to be retired and all Let's Encrypt users publishing DANE-TA(2) TLSA records need to update their TLSA records to publish additional records that will match the upcoming replacement CAs.

Specifically, there are multiple Let's Encrypt new issuer certificates that will potentially be used in automated certificate renewals: two primary certificates ("R3" and "E1") and their emergency backups ("R4" and "E2"). Thus, SMTP server operators using DANE-TA(2) with Let's Encrypt certificates must publish the following list of TLSA records (possibly in addition to "3 1 1" records matching the server public key) for each of their MX hosts in order to prevent delivery failures:

CA tagRecommended TLSA Records to match Let's Encrypt issuer CAs
X3_25._tcp.each.mx.host. IN TLSA 2 1 1 60b87575447dcba2a36b7d11ac09fb24a9db406fee12d2cc90180517616e8a18
X4_25._tcp.each.mx.host. IN TLSA 2 1 1 b111dd8a1c2091a89bd4fd60c57f0716cce50feeff8137cdbee0326e02cf362b
E1_25._tcp.each.mx.host. IN TLSA 2 1 1 276fe8a8c4ec7611565bf9fce6dcace9be320c1b5bea27596b2204071ed04f10
E2_25._tcp.each.mx.host. IN TLSA 2 1 1 bd936e72b212ef6f773102c6b77d38f94297322efc25396bc3279422e0c89270
R3_25._tcp.each.mx.host. IN TLSA 2 1 1 8d02536c887482bc34ff54e41d2ba659bf85b341a0a20afadb5813dcfbcf286d
R4_25._tcp.each.mx.host. IN TLSA 2 1 1 e5545e211347241891c554a03934cde9b749664a59d26d615fe58f77990f2d03

Once Let's Encrypt starts renewing server certificates via the new CAs, MX hosts whose TLSA records include only the "X3" digest may be unable to receive email from sending systems that perform DANE validation.

The MX host table below is sorted to list hosts that serve the most domains at the top.

signed domainshost name
3864mx.inetadmin.sk
3862mx.inetadmin.cz
3862mx.inetadmin.eu
180hosting01.spotler.net
177mailbackup.daxisweb.net
163hosting03.spotler.net
86ams0.the-net.nl
86mail.sciver.net
80barracuda.daxisweb.net
79barracuda3.daxisweb.net
78barracuda2.daxisweb.net
60web.carien.eu
57mx2.vos-systems.net
57mx3.vos-systems.net
57mx4.vos-systems.net
56mail.seolando.de
51rtm0.the-net.nl
48mx1.vos-systems.net
48vps.greenbull.it
40mx1.webmeneer.net
40mx2.webmeneer.net
33email.vlm.net
26dukun.de
22mail.headsite.se
20mx1.vicugna.nl
19clancy.halpanet.org
19mx1.dtsi.eu
18mail.semark.dk
18mail.sig-io.nl
18smtp.muehlberger.net
18web1.ams.dcg.t-host.net
17backup-mx.muehlberger.net
17mail.odissee.net
17smtp.astrath.net
15mail.aprendere.se
14mail.sysnull.net
14smtp3.strotmann.de
13mail1.zillner.it
13mx.it-zahner.net
13mx.no-spam-here.com
13mx1.mxspamfilter.de
12srv01.gosebrink.de
11mail-01.eu-central-1.aorta.space
11mail-02.eu-central-1.aorta.space
11mail-03.eu-central-1.aorta.space
11server.softcat.org
11srv02.gosebrink.de
1001z.eu
10alt1.mail.leonklingele.de
10alt2.mail.leonklingele.de
10alt3.mail.leonklingele.de
10alt4.mail.leonklingele.de
10mail.leonklingele.de
9geneos.wkmn-web.eu
9mail.7ujm.de
9mail2.7ujm.de
8artus.derflob.de
8mail.amberger.it
8mail.campana.email
8mail.fetzig.org
8mail.gnb-mail.dk
8mx1.serveur.nl
8neef-media.de
8rellim.com
8smithers.halpanet.org
7jolteon.boothlabs.me
7mail.dohd.org
7mail.fortweg.de
7mail.niklas-abel.de
7mail01.ipfire.org
7mail1.tootai.net
7mx.h.xup.link
7mx.sisv.eu
7mx01.lars-lehmann.net
7smtp.net4visions.de
7sys1.mmini.de
6asterix.lmlr.de
6eurekamaru.vrhein.de
6mail.calligo.nl
6mail.js86.de
6mail.rehost.eu
6mail.schem.me
6mail145.server.simon-mueller.de
6mail2.tootai.net
6mercury.mmvb.nl
6mx.casanapoli.eu
6mx.nameservice.dk
6mx1.elvikingo.de
6mx1.nerdpol.org
6mx2.mxspamfilter.de
6vm-1.eveng.de
5carien.eu
5courriel1.nomagic.fr
5courriel2.nomagic.fr
5hbackup.amberger.it
5mail.argantiu.de
5mail.bronk.de
5mail.felsing.net
5mail.jth.net
5mail.tgbartlett.net
5mail.viel.de
5mx.ahlers-online.de
5mx.bsdsystems.de
5santhie.wilane.org
5server.gropp.org
5wmd1.bitshared.eu
4admin50.tmkis.com
4blue.xy1.nl
4daemon.microwave.sk
4devold.4f.no
4dsrun.de
4email.anzuenden.jetzt
4fornax.divjak.at
4hoedown.de
4magellan.divjak.at
4mail.anguta.net
4mail.asda.gr
4mail.c-cinema.nl
4mail.criena.net
4mail.dadosch.de
4mail.genano.de
4mail.golima.de
4mail.jo8.de
4mail.laesche.eu
4mail.laesche.net
4mail.n-mail.li
4mail.patrickheyer.com
4mail.quux.de
4mail.region46.de
4mail.tuxit.be
4mail.yoshi.ovh
4mail01.schmalfeld-it.de
4mail1.viel.de
4mailgw1.itsecf.de
4mailgw2.itsecf.de
4mailgw3.itsecf.de
4mx.bauhaus.cc
4mx.boxencrypt.com
4mx.wkmn-web.eu
4mx1.lohmann.net.br
4mx2.asda.gr
4mx2.lohmann.net.br
4smtp.m31.zone
4sternschnuppe.bofh-noc.de
4web01.as49697.net
4yellow.xy1.nl
4zimbra.dreamradio.org
3blade.postuil.nl
3coruscant.sevenbyte.org
3filter.hattink.com
3hades62.meppel.nl
3hederahelix.oakforest.in
3mail-02.own-mail.eu
3mail.2c0.de
3mail.ajgon.ovh
3mail.cpfroehlich.de
3mail.cursed.space
3mail.dahuaidan.net
3mail.devshm.de
3mail.hr2server.de
3mail.incertum.net
3mail.iridiummail.org
3mail.marcel-geiling.de
3mail.mc-w.eu
3mail.medien-selber-machen.de
3mail.mirtouf.fr
3mail.piratenexus.com
3mail.postia.de
3mail.vandersterre-it.nl
3mail6.jth.net
3mailer.zeitschel.net
3mx.n0.lt
3mx2.pgollor.de
3prod-demo000.zivver.net
3rhodos.arminpech.de
3s1.luminary.pl
3srv.luminary.pl
3vps-s.laussat.de
3vps1.piconet.eu
3win.uwe.wtf
2arrakeen.geekwu.org
2ben.mdewendt.de
2box.mweho.xyz
2box.port587.xyz
2eclipse.servonline.de
2epsilon.h6g-server.net
2eva-00.fpob.cz
2fire.crza.de
2gloria.sntech.de
2grid.webcon.ca
2hal.ws-team.de
2hermine.thw-hermeskeil.de
2indigo.securenic.net
2ithil.bigon.be
2j5y.de
2lambda.h6g-server.net
2lucche.se
2mail.2bis10.de
2mail.agilitasus.net
2mail.bella.network
2mail.blinkt.de
2mail.bocloud.eu
2mail.cghc.de
2mail.cloudvoormail.nl
2mail.geekify.de
2mail.hardfalcon.net
2mail.ls-srv.de
2mail.manima.de
2mail.mental.cash
2mail.mischke.it
2mail.netpixeldesign.net
2mail.ornago.de
2mail.otvi.nl
2mail.patthemav.com
2mail.pleijster.nl
2mail.plusma.gr
2mail.rije.de
2mail.rit.space
2mail.rootsland.net
2mail.sportvereine.online
2mail.stark-walzen.eu
2mail.state-of-mind.de
2mail.syndace.com
2mail.themavlive.com
2mail.vmaurik.nl
2mail.zoopnet.de
2mail.zzyzz.de
2mail01.canzler-dv.de
2mail2.coffes.se
2mail2.sciver.net
2mailgw.dls-belgium.com
2mailgw2.dls-belgium.com
2mandelbrot.zaphods.net
2merkur.saurbier.net
2munchen.trost.se
2mupp.mupps.se
2mx.techthisout.de
2mx01.kleckerbox.de
2mx02.c-schmidt.eu
2mx02.kleckerbox.de
2mx1.dserver.net
2mx1.effeffcee.de
2mx1.pgollor.de
2mx1.us-east.qwop.net
2mx1.us-west.qwop.net
2mx2.dserver.net
2ns1.ednodarvo.io
2p2k.at
2plesk.247guide.nl
2prokyon.microscopium.de
2prometheus.mareo.fr
2s1.luqsus.pl
2smtp-de.adviser.com
2smtp.dipag.com
2smtp.servers.sciuro.org
2smx001.mao.systems
2smx002.mao.systems
2tim.mdewendt.de
2vmail1.greenie.net
2vps.sufliarsky.sk
2vserver01.christian-burgert.de
2vserver02.christian-burgert.de
1a.mx.homeunix.org.uk
1a.mx.homeunix.uk
1alberto.deller.id.au
1alewijn.eu
1ani-man.de
1ax1.keerl-it.com
1aykevl.nl
1b.mx.homeunix.org.uk
1b.mx.homeunix.uk
1bartmar.nl
1bartmarinissen.nl
1behoudvinkenhof.nl
1bmx.mischke.it
1brieftaube.millharrow.com
1bruno.faust.nom.br
1buma-fm.nl
1cantando.nl
1cb.100ny.net
1cdawoerden.org
1cheers.net
1choudhury.eu
1cjt-beerepoot.nl
1creatiefcollectiefelst.nl
1curve.hertzkurve.de
1dc.shadowcp.eu
1deparksegaard.nl
1devrandom.ru
1dilafoladi.nl
1dpsmassage.nl
1eipi1.thomas-bahn.net
1ej-uttenreuth.de
1enterprise-colonies.com
1et-inf.de
1eu-central-1.mx-1.pushto.space
1fmentertrainment.nl
1foladi.nl
1foob4r.org
1frankkesseleer.nl
1gindelmer.tangoz.de
1giurista.nl
1hetnieuwehuisvesten.nl
1hulpdienstelst.nl
1immolead-generator.de
1improtheatervoordeleeuwen.nl
1jansendermatografie.nl
1jrbv.nl
1kif.lord.re
1kolmann.at
1kzk.bunbun.be
1leakfix.nl
1logisciel.com
1lutetia.cartapus.eu
1m.duiadns.net
1mail-in.bundy-dns.de
1mail.administratie-smits.nl
1mail.adorp-nood.nl
1mail.advancedconceptplating.com
1mail.ag-link.xyz
1mail.ahrain.net
1mail.ainouno.me
1mail.airhorn.de
1mail.altf3.nl
1mail.amtare.eu
1mail.annejan.com
1mail.arndt.pro
1mail.avantems.com
1mail.avonturenopreis.nl
1mail.battlehawks.de
1mail.beherit.pl
1mail.black-box.org
1mail.bmaehr.com
1mail.bobdig.de
1mail.bouckhorst.nl
1mail.catram.org
1mail.chaletbemiddeling-makkum.nl
1mail.chalets-makkum.nl
1mail.chaletsmakkum.nl
1mail.checkpointwizard.nl
1mail.cheung.nu
1mail.cphpvb.net
1mail.delainhosting.com
1mail.dincomputer.dk
1mail.djakov.com
1mail.dm4productions.com
1mail.dus.net
1mail.estroh.com
1mail.etha.nz
1mail.exquus.nl
1mail.fiesta-mk5-limited-edition.nl
1mail.florinsdelicatesse.nl
1mail.gamerangerz.de
1mail.goowiz.com
1mail.grenz-bonn.de
1mail.hermanjordan.nl
1mail.hetelzen.nl
1mail.hostingportal.eu
1mail.hoyle.me.uk
1mail.in-deco.nl
1mail.in42.de
1mail.ip7.eu
1mail.j3e.de
1mail.j45p3r.de
1mail.jabber.eu.org
1mail.jstn.nl
1mail.kathymuldervormgeving.nl
1mail.khgl.de
1mail.koehlerweb.org
1mail.kompas-it.net
1mail.koxha.de
1mail.kupferschmid.ch
1mail.lexmedia.ro
1mail.liebmann.com.de
1mail.lowcarb-thailand.com
1mail.lukysek.cz
1mail.makkumchalets.nl
1mail.massiveink.nl
1mail.mceng.at
1mail.mdma.rocks
1mail.meadowfen.farm
1mail.meddo.info
1mail.mindcode.de
1mail.mochikabu.com
1mail.mueller-benedikt.de
1mail.nascloud.org
1mail.nerdbase.de
1mail.ouinouin.eu
1mail.ovks.de
1mail.paardenliefhebber.be
1mail.pambo.de
1mail.pardon.cloud
1mail.peildatum.nl
1mail.planet4nerds.de
1mail.plevenlab.org
1mail.prowim.info
1mail.psychologischepraktijkphilips.nl
1mail.ptv.cz
1mail.pylex.de
1mail.qtpass.org
1mail.ralix.net
1mail.rehaag.net
1mail.reulitz.de
1mail.ringhofer.email
1mail.roelofmeijer.actor
1mail.ruttentuttels.nl
1mail.samsamconceptstore.nl
1mail.samundsarah.de
1mail.saranails.be
1mail.sccsolution.com
1mail.sebi.org
1mail.seenonline.nl
1mail.shaizen.net
1mail.shawfamily.id.au
1mail.smits.frl
1mail.snaphome.net
1mail.sullenholland.nl
1mail.teratorium.email
1mail.thashit.dk
1mail.tuempfel.de
1mail.tuxlinux.eu
1mail.uniquefysio.nl
1mail.unterhaltungsbox.com
1mail.uptheinter.net
1mail.urlaubmakkum.de
1mail.usys.sg
1mail.vanaerdesports.nl
1mail.vanmeerbouw.nl
1mail.vk1fj.net
1mail.voordejeugd.nl
1mail.waehlefamilie.de
1mail.web-wack.at
1mail.wellfit.nu
1mail.wiggershaus.net
1mail.wijsit.nl
1mail.wisecomnet.com
1mail.wolff.pro
1mail.wollmann.it
1mail.xmmswap.com
1mail.xn--tmpfel-3ya.de
1mail.xudonax.eu
1mail.yawara-ryu.nl
1mail.yenisley.nl
1mail.zmaloveane.pl
1mail01.wolkenputzen.de
1mail1.andreas-lemcke.de
1mail1.bobdig.de
1mail1.cotter.de
1mail1.dasprofil.net
1mail1.heinz-w-albert.de
1mail1.kf-events.de
1mail1.kleinerfalter.de
1mail1.reischauer.net
1mail1.sasel.org
1mail1.saselit.de
1mail1.saselsoft.de
1mail1.scharwaechter-reinbek.de
1mail1.tollemenschen.de
1mail1.wingsturlaub.de
1mail2.andreas-lemcke.de
1mail2.bobdig.de
1mail2.cotter.de
1mail2.dasprofil.net
1mail2.heinz-w-albert.de
1mail2.hermanjordan.nl
1mail2.kf-events.de
1mail2.kleinerfalter.de
1mail2.raecknetz.de
1mail2.reischauer.net
1mail2.sasel.org
1mail2.saselit.de
1mail2.saselsoft.de
1mail2.scharwaechter-reinbek.de
1mail2.sushitee.de
1mail2.teachersbrain.net
1mail2.tgbartlett.net
1mail2.tollemenschen.de
1mail2.usys.sg
1mail2.wingsturlaub.de
1mailgw.itsecf.de
1mailgw.lulaits.de
1mailgw.physiozeit-waldthurn.de
1marjadeleeuw.nl
1masrv.dedyn.io
1mcplayman.de
1medinaelst.nl
1melisandre.darkspacelab.com
1mrkrabat.de
1mx-01.nakene.com
1mx-n.loos.net
1mx.boehling.com
1mx.cainites.net
1mx.dev-urandom.net
1mx.iomaestro.net
1mx.janisluenne.de
1mx.mrwax.eu
1mx.schaltstube.de
1mx.shadowcp.eu
1mx.yaoyorozu.re
1mx01.gcsfb.de
1mx01.skyforge.at
1mx1.acodat.com
1mx1.alexhaase.de
1mx1.finalhosting.cz
1mx1.japlin.io
1mx1.kuhmunity.space
1mx1.mahlangeni.de
1mx2.boehling.com
1mx2.japlin.io
1mx2.mahlangeni.de
1mx3.loos.net
1mx5.adelton.com
1mx5.tlapka.com
1mx6.wkmn-web.eu
1natuurenkunst.nl
1nextiot.de
1nextrus.info
1nmeoverbetuwe.nl
1ns4.jth.net
1nyima.charpa.org
1overbetuwegroennatuurlijk.nl
1physiobalance.nl
1plesk2.acknowledge.nl
1post.karrenberg.net
1relay2.melnyk.lu
1ringehd.com
1rocqua.nl
1ryanrichardwalker.com
1santackergaard.nl
1saroverbetuwe.nl
1saskiaspaintings.nl
1schreursbto.nl
1sheilabaas.nl
1skeefindepanty.com
1skorpil.cz
1smtp.aeon-hq.net
1smtp.andreas-lemcke.de
1smtp.coldmail.cc
1smtp.cotter.de
1smtp.gmk.net.pl
1smtp.jvangent.com
1smtp.jvangent.nl
1smtp.kleinerfalter.de
1smtp.louwes.info
1smtp.reischauer.net
1smtp.sasel.org
1smtp.saselit.de
1smtp.saselsoft.de
1smtp.tollemenschen.de
1smtp.vdlaken.eu
1smtp2.jvangent.com
1smtp2.jvangent.nl
1speeleninstallatietechniek.nl
1spekman.eu
1srv.moreshop.pl
1srv.ncxs.de
1steengoedenmeer.nl
1tandarts.eu
1teamb.nl
1teleskop-seite.de
1thestoneage.de
1trainingsbureauvoorzorg.nl
1trimsalonelst.nl
1trustserv.de
1twanjansen.com
1twinbalance.nl
1ulrika.berget.nu
1velociraptor1.cschenk.net
1velociraptor2.cschenk.net
1vga-arcadis.nl
1vincedalucca.com
1vps.brmlab.cz
1vps.jell.ie
1vps1.kobezda.net
1vrouwenmetlefbetuwe.nl
1wakko.elb.net
1weerroden.nl
1yakko.elb.net