diff --git a/src/constants.rs b/src/constants.rs
index 057bb1f89..9edf40f8e 100644
--- a/src/constants.rs
+++ b/src/constants.rs
@@ -205,6 +205,11 @@ pub const WORSE_IMAGE_SIZE: u32 = 640;
 // this value can be increased if the folder configuration is changed and must be redone on next program start
 pub const DC_FOLDERS_CONFIGURED_VERSION: i32 = 3;
 
+// if more recipients are needed in SMTP's `RCPT TO:` header, recipient-list is splitted to chunks.
+// this does not affect MIME'e `To:` header.
+// can be overwritten by the setting `max_smtp_rcpt_to` in provider-db.
+pub const DEFAULT_MAX_SMTP_RCPT_TO: usize = 50;
+
 #[derive(
     Debug,
     Display,
diff --git a/src/provider/data.rs b/src/provider/data.rs
index 91ef3067f..bb850c86e 100644
--- a/src/provider/data.rs
+++ b/src/provider/data.rs
@@ -32,6 +32,7 @@ static P_AKTIVIX_ORG: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -46,6 +47,7 @@ static P_AOL: Lazy<Provider> = Lazy::new(|| {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 }
 });
@@ -74,6 +76,7 @@ static P_ARCOR_DE: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -101,6 +104,7 @@ static P_AUTISTICI_ORG: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -128,6 +132,7 @@ static P_BLUEWIN_CH: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -155,6 +160,7 @@ static P_BUZON_UY: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: true,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -182,6 +188,7 @@ static P_CHELLO_AT: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -194,6 +201,7 @@ static P_COMCAST: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -206,6 +214,7 @@ static P_DISMAIL_DE: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -218,6 +227,7 @@ static P_DISROOT: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: true,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -269,6 +279,7 @@ static P_DUBBY_ORG: Lazy<Provider> = Lazy::new(|| Provider {
         },
     ]),
     strict_tls: true,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -285,6 +296,7 @@ static P_EXAMPLE_COM: Lazy<Provider> = Lazy::new(|| {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 }
 });
@@ -299,6 +311,7 @@ static P_FASTMAIL: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -313,6 +326,7 @@ static P_FIREMAIL_DE: Lazy<Provider> = Lazy::new(|| {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 }
 });
@@ -343,6 +357,7 @@ static P_FIVE_CHAT: Lazy<Provider> = Lazy::new(|| Provider {
         },
     ]),
     strict_tls: true,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -370,6 +385,7 @@ static P_FREENET_DE: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -386,6 +402,7 @@ static P_GMAIL: Lazy<Provider> = Lazy::new(|| {
     ],
     config_defaults: None,
     strict_tls: true,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: Some(Oauth2Authorizer::Gmail),
 }
 });
@@ -421,6 +438,7 @@ static P_GMX_NET: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -450,6 +468,7 @@ static P_HERMES_RADIO: Lazy<Provider> = Lazy::new(|| Provider {
         },
     ]),
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -464,6 +483,7 @@ static P_HEY_COM: Lazy<Provider> = Lazy::new(|| {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 }
 });
@@ -477,6 +497,7 @@ static P_I_UA: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -505,6 +526,7 @@ static P_ICLOUD: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -517,6 +539,7 @@ static P_KOLST_COM: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -529,6 +552,7 @@ static P_KONTENT_COM: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -541,6 +565,7 @@ static P_MAIL_RU: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -553,6 +578,7 @@ static P_MAILBOX_ORG: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: true,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -578,6 +604,7 @@ static P_NAUTA_CU: Lazy<Provider> = Lazy::new(|| {
         ConfigDefault { key: Config::FetchExistingMsgs, value: "0" },
     ]),
     strict_tls: false,
+    max_smtp_rcpt_to: Some(20),
     oauth2_authorizer: None,
 }
 });
@@ -595,6 +622,7 @@ static P_OUTLOOK_COM: Lazy<Provider> = Lazy::new(|| {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 }
 });
@@ -623,6 +651,7 @@ static P_POSTEO: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: true,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -637,6 +666,7 @@ static P_PROTONMAIL: Lazy<Provider> = Lazy::new(|| {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 }
 });
@@ -650,6 +680,7 @@ static P_RISEUP_NET: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: true,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -662,6 +693,7 @@ static P_ROGERS_COM: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -674,6 +706,7 @@ static P_SYSTEMLI_ORG: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: true,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -688,6 +721,7 @@ static P_T_ONLINE: Lazy<Provider> = Lazy::new(|| {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 }
 });
@@ -740,6 +774,7 @@ static P_TESTRUN: Lazy<Provider> = Lazy::new(|| Provider {
         },
     ]),
     strict_tls: true,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -767,6 +802,7 @@ static P_TISCALI_IT: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -779,6 +815,7 @@ static P_UKR_NET: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -806,6 +843,7 @@ static P_UNDERNET_UY: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: true,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -818,6 +856,7 @@ static P_VFEMAIL: Lazy<Provider> = Lazy::new(|| Provider {
     server: vec![],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -845,6 +884,7 @@ static P_VODAFONE_DE: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -862,6 +902,7 @@ static P_WEB_DE: Lazy<Provider> = Lazy::new(|| {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 }
 });
@@ -879,6 +920,7 @@ static P_YAHOO: Lazy<Provider> = Lazy::new(|| {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 }
 });
@@ -907,6 +949,7 @@ static P_YANDEX_RU: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: true,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: Some(Oauth2Authorizer::Yandex),
 });
 
@@ -934,6 +977,7 @@ static P_ZIGGO_NL: Lazy<Provider> = Lazy::new(|| Provider {
     ],
     config_defaults: None,
     strict_tls: false,
+    max_smtp_rcpt_to: None,
     oauth2_authorizer: None,
 });
 
@@ -1109,4 +1153,4 @@ pub static PROVIDER_DATA: Lazy<HashMap<&'static str, &'static Provider>> = Lazy:
 });
 
 pub static PROVIDER_UPDATED: Lazy<chrono::NaiveDate> =
-    Lazy::new(|| chrono::NaiveDate::from_ymd(2020, 10, 22));
+    Lazy::new(|| chrono::NaiveDate::from_ymd(2020, 10, 30));
diff --git a/src/provider/mod.rs b/src/provider/mod.rs
index bbc1e39cc..57133f56e 100644
--- a/src/provider/mod.rs
+++ b/src/provider/mod.rs
@@ -75,6 +75,7 @@ pub struct Provider {
     pub server: Vec<Server>,
     pub config_defaults: Option<Vec<ConfigDefault>>,
     pub strict_tls: bool,
+    pub max_smtp_rcpt_to: Option<u16>,
     pub oauth2_authorizer: Option<Oauth2Authorizer>,
 }
 
diff --git a/src/provider/update.py b/src/provider/update.py
index 0d91687c1..2a045ab18 100755
--- a/src/provider/update.py
+++ b/src/provider/update.py
@@ -104,6 +104,9 @@ def process_data(data, file):
     strict_tls = data.get("strict_tls", False)
     strict_tls = "true" if strict_tls else "false"
 
+    max_smtp_rcpt_to = data.get("max_smtp_rcpt_to", 0)
+    max_smtp_rcpt_to = "Some(" + str(max_smtp_rcpt_to) + ")" if max_smtp_rcpt_to != 0 else "None"
+
     oauth2 = data.get("oauth2", "")
     oauth2 = "Some(Oauth2Authorizer::" + camel(oauth2) + ")" if oauth2 != "" else "None"
 
@@ -119,6 +122,7 @@ def process_data(data, file):
         provider += "    server: vec![\n" + server + "    ],\n"
         provider += "    config_defaults: " + config_defaults + ",\n"
         provider += "    strict_tls: " + strict_tls + ",\n"
+        provider += "    max_smtp_rcpt_to: " + max_smtp_rcpt_to + ",\n"
         provider += "    oauth2_authorizer: " + oauth2 + ",\n"
         provider += "});\n\n"
     else:
diff --git a/src/smtp/send.rs b/src/smtp/send.rs
index 4ffa64682..561820010 100644
--- a/src/smtp/send.rs
+++ b/src/smtp/send.rs
@@ -3,8 +3,11 @@
 use super::Smtp;
 use async_smtp::*;
 
+use crate::config::Config;
+use crate::constants::DEFAULT_MAX_SMTP_RCPT_TO;
 use crate::context::Context;
 use crate::events::EventType;
+use crate::provider::get_provider_info;
 use itertools::Itertools;
 use std::time::Duration;
 
@@ -34,37 +37,51 @@ impl Smtp {
     ) -> Result<()> {
         let message_len_bytes = message.len();
 
-        let recipients_display = recipients.iter().map(|x| x.to_string()).join(",");
-
-        let envelope =
-            Envelope::new(self.from.clone(), recipients).map_err(Error::EnvelopeError)?;
-        let mail = SendableEmail::new(
-            envelope,
-            format!("{}", job_id), // only used for internal logging
-            message,
-        );
-
-        if let Some(ref mut transport) = self.transport {
-            // The timeout is 1min + 3min per MB.
-            let timeout = 60 + (180 * message_len_bytes / 1_000_000) as u64;
-            transport
-                .send_with_timeout(mail, Some(&Duration::from_secs(timeout)))
+        let mut chunk_size = DEFAULT_MAX_SMTP_RCPT_TO;
+        if let Some(provider) = get_provider_info(
+            &context
+                .get_config(Config::ConfiguredAddr)
                 .await
-                .map_err(Error::SendError)?;
-
-            context.emit_event(EventType::SmtpMessageSent(format!(
-                "Message len={} was smtp-sent to {}",
-                message_len_bytes, recipients_display
-            )));
-            self.last_success = Some(std::time::SystemTime::now());
-
-            Ok(())
-        } else {
-            warn!(
-                context,
-                "uh? SMTP has no transport, failed to send to {}", recipients_display
-            );
-            Err(Error::NoTransport)
+                .unwrap_or_default(),
+        ) {
+            if let Some(max_smtp_rcpt_to) = provider.max_smtp_rcpt_to {
+                chunk_size = max_smtp_rcpt_to as usize;
+            }
         }
+
+        for recipients_chunk in recipients.chunks(chunk_size).into_iter() {
+            let recipients = recipients_chunk.to_vec();
+            let recipients_display = recipients.iter().map(|x| x.to_string()).join(",");
+
+            let envelope =
+                Envelope::new(self.from.clone(), recipients).map_err(Error::EnvelopeError)?;
+            let mail = SendableEmail::new(
+                envelope,
+                format!("{}", job_id), // only used for internal logging
+                &message,
+            );
+
+            if let Some(ref mut transport) = self.transport {
+                // The timeout is 1min + 3min per MB.
+                let timeout = 60 + (180 * message_len_bytes / 1_000_000) as u64;
+                transport
+                    .send_with_timeout(mail, Some(&Duration::from_secs(timeout)))
+                    .await
+                    .map_err(Error::SendError)?;
+
+                context.emit_event(EventType::SmtpMessageSent(format!(
+                    "Message len={} was smtp-sent to {}",
+                    message_len_bytes, recipients_display
+                )));
+                self.last_success = Some(std::time::SystemTime::now());
+            } else {
+                warn!(
+                    context,
+                    "uh? SMTP has no transport, failed to send to {}", recipients_display
+                );
+                return Err(Error::NoTransport);
+            }
+        }
+        Ok(())
     }
 }