Just experementing and noticed the default on Postfix Installations on Ubuntu 19
250 SMTPUTF8
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Post-Handshake New Session Ticket arrived:
SSL-Session:
Protocol : TLSv1.3
Cipher : TLS_AES_256_GCM_SHA384
Session-ID: 0B7D451B2ECDAAAFD6D25647B4D51A4516F9D80C5050ED5333E779A0D0C199F1
Session-ID-ctx:
Resumption PSK: 7A835C99E6A0DB7C0A37EA0D8E50C37C0912111FCFAB05505DC6046350A1B524F0E58EE969707E8D882E1D99C2A6F19D
PSK identity: None
PSK identity hint: None
SRP username: None
TLS session ticket lifetime hint: 7200 (seconds)
TLS session ticket:
0000 - 8d b5 f1 1a 81 a8 14 40-6a b2 18 0c 78 35 77 bf .......@j...x5w.
0010 - 9f 14 93 09 82 3a 13 c4-0d 35 bd 4c 60 f9 ef 65 .....:...5.L`..e
0020 - 39 dc 61 61 20 2a ae 23-92 08 05 36 9c 50 cc 5c 9.aa *.#...6.P.\
0030 - 56 b0 ba 42 08 69 3c 08-cc bb 3a a7 af 84 a1 57 V..B.i<...:....W
0040 - 26 26 71 bf ae bc 66 8e-53 c2 e0 30 35 52 c3 c2 &&q...f.S..05R..
0050 - b7 46 1d 7c dd ec 50 5b-2e 26 28 7c cc 06 1d aa .F.|..P[.&(|....
0060 - 07 1f 9c 65 c9 40 3e 2c-a9 09 9b 1a c6 f7 1d 1c ...e.@>,........
0070 - 01 ad 3a 2d ad 86 bd 5c-cd a2 9c c2 4e f3 fa 8b ..:-...\....N...
0080 - 08 9b 14 86 ee 04 b3 83-6e 03 1f 26 98 56 4e 15 ........n..&.VN.
0090 - f5 fa 5f f0 11 c8 e3 da-4c a7 11 f1 d8 b7 1b e8 .._.....L.......
00a0 - 11 3e d8 18 0f 7f da 27-e6 17 b2 2f 0e d8 17 0a .>.....'.../....
00b0 - a6 c4 9b 9e f4 81 2e 33-0f 08 ab cb b9 fc 81 72 .......3.......r
00c0 - 8f 49 3a 70 e9 cb 25 c9-81 c9 8a 15 b8 c0 00 5c .I:p..%........\
Start Time: 1556469043
Timeout : 7200 (sec)
Verify return code: 0 (ok)
Extended master secret: no
Max Early Data: 0
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read R BLOCK