Let me provide the raw data for you to look at. Feel free to double check the results on your own. There are some who hide behind email protection services recently and I used an internet archival service to check the previous MX records before they used the protection service. Best assumption I could have made and I could be wrong on some of them but the margin of error I feel is small.
| Top 103 Churches in USA | City | State | Congregation Size | Email Provider |
|---|---|---|---|---|
| Lifechurch.TV | Edmond | OK | 70000 | Office365 |
| Lakewood Church | Houston | TX | 52000 | Office365 |
| South Baptist Church | Houston | TX | 23659 | Self-Hosted |
| North Point Community Church | Alpharetta | GA | 22557 | |
| WILLOW CREEK COMMUNITY CHURCH | South Barrington | IL | 22500 | Office365 |
| WEST ANGELES CATHEDRAL | Los Angeles | CA | 20000 | |
| Fellowship Church (Ps Ed Young Jr) | Grapevine | TX | 19913 | Office365 |
| Saddleback Church (Ps Rick Warren) | Lake Forest | CA | 19414 | Office365 |
| CALVARY CHAPEL FORT LAUDERDALE | Fort Lauderdale | FL | 18000 | Self-Hosted |
| The Potter’s House (Ps TD Jakes) | Dallas | TX | 17000 | Office365 |
| Woodlands Church | The Woodlands | TX | 16380 | Office365 |
| SOUTHEAST CHRISTIAN CHURCH | Louisville | KY | 16264 | Self-Hosted |
| HOPEWELL MISSIONARY BAPTIST | Norcross | GA | 16000 | Web Host |
| NEW BIRTH MISSIONARY BAPTIST | Lithonia | GA | 15000 | Mailanyone |
| NORTHRIDGE CHURCH | Plymouth | MI | 14762 | Microsoft Exchange |
| NEW HOPE CHRISTIAN FELLOWSHIP | Honolulu | HI | 14500 | |
| PRESTONWOOD BAPTIST CHURCH | Plano | TX | 14450 | Self-Hosted |
| MCLEAN BIBLE CHURCH (Ps Lon Solomon) | McLean | VA | 13699 | Office365 |
| FIRST BAPTIST CHURCH HAMMOND (Ps Jack Schaap) | Hammond | IN | 13678 | Office365 |
| CALVARY OF ALBUQUERQUE | Albuquerque | NM | 13500 | |
| NEW LIGHT CHRISTIAN CENTER CHURCH | Houston | TX | 13500 | GoDaddy |
| CENTRAL CHURCH | Henderson | NV | 13010 | |
| THOMAS ROAD BAPTIST CHURCH (Ps Jonathan Falwell) | Lynchburg | VA | 13000 | Office365 |
| CHRIST’S CHURCH OF THE VALLEY | Peoria | AZ | 12535 | Self-Hosted |
| CHRIST FELLOWSHIP | Palm Beach Gardens | FL | 12339 | Self-Hosted |
| COMMUNITY BIBLE CHURCH | San Antonio | TX | 12120 | Self-Hosted |
| CALVARY CHAPEL GOLDEN SPRINGS | Diamond Bar | CA | 12000 | |
| HARVEST CHRISTIAN FELLOWSHIP (Ps Greg Laurie) | Riverside | CA | 12000 | Office365 |
| FOUNTAIN OF PRAISE | Houston | TX | 11752 | Web Host |
| FREE CHAPEL WORSHIP CENTER | Gainesville | GA | 11500 | Self-Hosted |
| LAKE POINTE CHURCH (Ps Steve Stroope) | Rockwall | TX | 11133 | Office365 |
| HARVEST BIBLE CHAPEL | Rolling Meadows | IL | 10988 | |
| THE ROCK CHURCH | San Diego | CA | 10878 | Web Host |
| VALLEY BIBLE FELLOWSHIP | Bakersfield | CA | 10800 | |
| FAMILY CHRISTIAN CENTER (Ps Steve Munsey) | Munster | IN | 10600 | Office365 |
| CROSSROADS | Cincinnati | OH | 10556 | |
| KENSINGTON COMMUNITY CHURCH (Ps Steve Andrews | Troy | MI | 10484 | Office365 |
| ) | ||||
| EAGLE BROOK CHURCH | Hugo | MN | 10334 | Office365 |
| Gateway Church (Ps Robert Morris) | Southlake | TX | 10170 | Office365 |
| BAYSIDE COVENANT CHURCH | Roseville | CA | 10052 | Office365 |
| ST. MATTHEWS BAPTIST CHURCH | Williamstown | NJ | 10035 | Self-Hosted |
| FAITH COMMUNITY CHURCH | West Covina | CA | 10000 | Self-Hosted |
| FAITH LANDMARKS MINISTRIES | Richmond | VA | 10000 | Self-Hosted |
| 1ST AFRICAN METHODIST EPISCOPAL | Los Angeles | CA | 10000 | Office365 |
| HERITAGE CHRISTIAN CENTER | Denver | CO | 10000 | |
| MOUNT ZION BAPTIST CHURCH | Nashville | TN | 10000 | Office365 |
| WORLD CHANGERS CHURCH INT. | College Park | GA | 10000 | Self-Hosted |
| CALVARY CHAPEL SOUTH BAY | Gardena | CA | 9600 | Office365 |
| ABUNDANT LIVING FAITH CENTER | El Paso | TX | 9500 | Office365 |
| CALVARY CHAPEL OF COSTA MESA | Santa Ana | CA | 9500 | Self-Hosted |
| SOUTHLAND CHRISTIAN CHURCH | Lexington | KY | 9358 | |
| SEACOAST CHURCH | Mt Pleasant | SC | 9232 | Microsoft Exchange |
| FAITH FELLOWSHIP OUTREACH CENTER | Sayreville | NJ | 9200 | Office365 |
| SALEM BAPTIST CHURCH | Chicago | IL | 9137 | Office365 |
| CHRISTIAN CULTURAL CENTER | Brooklyn | NY | 9000 | Self-Hosted |
| CHRISTIAN FAITH CENTER | Federal Way | WA | 9000 | Self-Hosted |
| CHURCH OF THE RESURRECTION | Leawood | KS | 9000 | Office365 |
| MARINERS CHURCH | Irvine | CA | 9000 | |
| REDEMPTION WORLD OUTREACH CENTER | Greenville | SC | 9000 | Office365 |
| SAINT STEPHEN CHURCH | Louisville | KY | 9000 | Mailanyone |
| THE ROCK CHURCH & OUTREACH | San Bernardino | CA | 9000 | Self-Hosted |
| NORTHLAND, A CHURCH DISTRIBUTED | Longwood | FL | 8792 | |
| SA-RANG COMMUNITY CHURCH | Anaheim | CA | 8750 | |
| CALVARY CHAPEL CHINO VALLEY | Chino | CA | 8500 | Office365 |
| CORNERSTONE CHURCH | San Antonio | TX | 8406 | Self-Hosted |
| REAL LIFE MINISTRIES | Post Falls | ID | 8400 | |
| ANGELUS TEMPLE | Los Angeles | CA | 8272 | |
| GRACE COMMUNITY CHURCH | Sun Valley | CA | 8258 | Office365 |
| THE CHURCH WITHOUT WALLS | Houston | TX | 8250 | Office365 |
| ST. JOHN BAPTIST CHURCH | Grand Prairie | TX | 8200 | Office365 |
| CHURCH OF THE HIGHLANDS | Birmingham | AL | 8168 | Microsoft Exchange |
| BETHEL BAPTIST INSTITUTIONAL CHURCH | Jacksonville | FL | 8168 | Office365 |
| FLAMINGO ROAD CHURCH | Cooper City | FL | 8005 | |
| BETHANY WORLD PRAYER CENTER | Baker | LA | 8000 | |
| CALVARY CHAPEL MELBOURNE | West Melbourne | FL | 8000 | Self-Hosted |
| CALVARY CHAPEL OF PHILADELPHIA | Philadelphia | PA | 8000 | Self-Hosted |
| COVENANT CHURCH | Carrollton | TX | 8000 | Office365 |
| FELLOWSHIP BIBLE CHURCH | Rogers | AR | 8000 | Office365 |
| NEW LIFE CHURCH | Colorado Springs | CO | 8000 | Office365 |
| TIMES SQUARE CHURCH | New York | NY | 8000 | Office365 |
| HICKORY GROVE BAPTIST CHURCH | Charlotte | NC | 7900 | Office365 |
| NEWSPRING CHURCH | Anderson | SC | 7726 | |
| JAMES RIVER ASSEMBLY | Ozark | MO | 7716 | Office365 |
| LANCASTER COUNTY BIBLE CHURCH | Manheim | PA | 7652 | GoDaddy |
| CHURCH OF THE REDEEMED OF THE LORD | Baltimore | MD | 7500 | Web Host |
| HOPE PRESBYTERIAN CHURCH | Cordova | TN | 7500 | Office365 |
| INSPIRING BODY OF CHRIST CHURCH | Dallas | TX | 7500 | Self-Hosted |
| REID TEMPLE A.M.E. CHURCH | Glenn Dale | MD | 7500 | GoDaddy |
| THE GREATER ALLEN CATHEDRAL OF NY | Jamaica | NY | 7500 | Self-Hosted |
| THE LIVING WORD BIBLE CHURCH | Mesa | AZ | 7500 | GoDaddy |
| CENTRAL CHRISTIAN CHURCH E. VALLEY | Mesa | AZ | 7425 | |
| SHEPHERD OF THE HILLS CHURCH | Porter Ranch | CA | 7400 | Office365 |
| CALVARY TEMPLE WORSHIP CENTER | Modesto | CA | 7335 | GoDaddy |
| FLATIRONS COMMUNITY CHURCH | Lafayette | CO | 7200 | Office365 |
| IGLESIA CRISTIANA SEGADORES DE VIDA | Hollywood | FL | 7069 | |
| CELEBRATION CHURCH | Jacksonville | FL | 7015 | Office365 |
| ANTIOCH MISSIONARY BAPTIST CHURCH | Miami | FL | 7000 | Self-Hosted |
| CALVARY CHAPEL DOWNEY | Downey | CA | 7000 | Office365 |
| ELMBROOK CHURCH | Brookfield | WI | 7000 | Office365 |
| FIRST BAPTIST CHURCH JACKSONVILLE | Jacksonville | FL | 7000 | Office365 |
| FIRST BAPTIST CHURCH ORLANDO | Orlando | FL | 7000 | Office365 |
| MARANATHA CHAPEL | San Diego | CA | 7000 | Microsoft Exchange |
| THE CHAPEL | Akron | OH | 7000 | Office365 |