The output from querying for TXT records for the global bank HSBC:
hsbc.com. 300 IN TXT "c77e0dfe9d1771b49cbbf615650b24e"
hsbc.com. 300 IN TXT "8219-5848-B517-278B-A270-122C-5E8F-C5ED"
hsbc.com. 300 IN TXT "6F33-A96D-4A70-B2F3-8980-0DA9-C687-9C2F"
hsbc.com. 300 IN TXT "5700a0f161c3ee56b1cdb45f8ff0d606"
hsbc.com. 300 IN TXT "v=spf1 include:spf-00299f02.pphosted.com include:spf1.hsbc.com include:spf2.hsbc.com include:spf3.hsbc.com ~all"
hsbc.com. 300 IN TXT "f9fe8b945d159604d4fe56f68fd5a851"
hsbc.com. 300 IN TXT "7c573538-4895-4bd2-90b9-13ecb67623b3"
hsbc.com. 300 IN TXT "mongodb-site-verification=IZGVt2wuFTz4U2KdEQTxNjbTM5MQ4agI"
hsbc.com. 300 IN TXT "docker-verification=2885f98d-883c-4171-88f5-44ebc35fd452"
hsbc.com. 300 IN TXT "_github-challenge-hsbc-ent.hsbc.com=2c0124c517"
hsbc.com. 300 IN TXT "google-site-verification=NI7zII4Ge_p28m0XfsDGMj77Nly4XabBi4MonUEVcUM"
hsbc.com. 300 IN TXT "google-site-verification=vPkZv7fjzUVwP2apQBxXmbtPQb0PAhU5k9KuxnAwr5o"
hsbc.com. 300 IN TXT "google-site-verification=M4iN_PX9kRTMMWq44Gj5N0yCKw21840zwBXdoBk1XJM"
hsbc.com. 300 IN TXT "adobe-idp-site-verification=97bd1b56bb7c1bf2b021fcc1aa99f303be57821beda2e03442612fe631a071e5"
hsbc.com. 300 IN TXT "webexdomainverification.=de5860e7-75ed-4687-9345-095d6298d12b"
hsbc.com. 300 IN TXT "webexdomainverification.=e10dece0-359f-4aa8-85f9-8fd61121b3c1"
hsbc.com. 300 IN TXT "webexdomainverification.JO59=608c80a0-fcc1-4022-8b7f-d99cee31b523"
hsbc.com. 300 IN TXT "webexdomainverification.GVLY=f509eddc-026a-40ff-896d-94a2a7c5089a"
hsbc.com. 300 IN TXT "webexdomainverification.L2W7=69ac8949-902f-4c8c-90d0-4a0d3dcedb1c"
hsbc.com. 300 IN TXT "webexdomainverification.L2W2=72eed45f-93c2-4f58-8c1f-407b22083b6c"
hsbc.com. 300 IN TXT "webexdomainverification.=cf1ab7f9-8d4c-4d37-aff4-4a88b437614c"
hsbc.com. 300 IN TXT "96b06eef013a4fa7ba21975d52f6cea8ba5586141e604aad968e8e8a6a6b0d0c"
hsbc.com. 300 IN TXT "adobe-sign-verification=33807990c7278c58bea18223c41dcf38"
From this output there is evidence of use of Google, Adobe, MongoDB, Docker, GitHub, Webex and Proofpoint as an email gateway.