feat: Remove limit on number of email recipients for chatmail clients (#5598)

src/chat.rs

@@ -2995,11 +2995,7 @@ pub(crate) async fn create_send_msg_jobs(context: &Context, msg: &mut Message) -
 
     msg.subject.clone_from(&rendered_msg.subject);
     msg.update_subject(context).await?;
-    let chunk_size = context
-        .get_configured_provider()
-        .await?
-        .and_then(|provider| provider.opt.max_smtp_rcpt_to)
-        .map_or(constants::DEFAULT_MAX_SMTP_RCPT_TO, usize::from);
+    let chunk_size = context.get_max_smtp_rcpt_to().await?;
     let trans_fn = |t: &mut rusqlite::Transaction| {
         let mut row_ids = Vec::<i64>::new();
         for recipients_chunk in recipients.chunks(chunk_size) {

src/context.rs

@@ -498,6 +498,23 @@ impl Context {
         self.get_config_bool(Config::IsChatmail).await
     }
 
+    /// Returns maximum number of recipients the provider allows to send a single email to.
+    pub(crate) async fn get_max_smtp_rcpt_to(&self) -> Result<usize> {
+        let is_chatmail = self.is_chatmail().await?;
+        let val = self
+            .get_configured_provider()
+            .await?
+            .and_then(|provider| provider.opt.max_smtp_rcpt_to)
+            .map_or_else(
+                || match is_chatmail {
+                    true => usize::MAX,
+                    false => constants::DEFAULT_MAX_SMTP_RCPT_TO,
+                },
+                usize::from,
+            );
+        Ok(val)
+    }
+
     /// Does a background fetch
     /// pauses the scheduler and does one imap fetch, then unpauses and returns
     pub async fn background_fetch(&self) -> Result<()> {

src/sql/migrations.rs

@@ -5,7 +5,7 @@ use deltachat_contact_tools::EmailAddress;
 use rusqlite::OptionalExtension;
 
 use crate::config::Config;
-use crate::constants::{self, ShowEmails};
+use crate::constants::ShowEmails;
 use crate::context::Context;
 use crate::imap;
 use crate::message::MsgId;
@@ -839,11 +839,7 @@ CREATE INDEX msgs_status_updates_index2 ON msgs_status_updates (uid);
 
     if dbversion < 108 {
         let version = 108;
-        let chunk_size = context
-            .get_configured_provider()
-            .await?
-            .and_then(|provider| provider.opt.max_smtp_rcpt_to)
-            .map_or(constants::DEFAULT_MAX_SMTP_RCPT_TO, usize::from);
+        let chunk_size = context.get_max_smtp_rcpt_to().await?;
         sql.transaction(move |trans| {
             Sql::set_db_version_trans(trans, version)?;
             let id_max =