diff --git a/src/lib/mail.ts b/src/lib/mail.ts
index 739ba2b..e323910 100644
--- a/src/lib/mail.ts
+++ b/src/lib/mail.ts
@@ -110,17 +110,22 @@ async function sendEmail(subject: string, html: string, cc?: string) {
 
 export const mail = {
 
-  onEstablished: (target: string, message = `Connection established for ${target}`, getHtml: () => string = () => `
+  onEstablished: (target: string,
+                  message: () => string|undefined = () => `Connection established for ${target}`,
+                  getHtml: () => string = () => `
       <p>
         Connection from [${os.hostname}] to ${target} established on ${moment().format('DD-MM-YYYY HH:mm:ss')}.
       </p>
     `) => {
     return async (cc?: string) => {
-      await queueEmail(`[dw] [${os.hostname}] ${message}`, getHtml(), cc)
+      await queueEmail(`[dw] [${os.hostname}] ${message()}`, getHtml(), cc)
     }
   },
 
-  onDisconnect: (target: string, message = `Connection closed for ${target}`, getErrorMessage: () => string = () => '', getHtml: (waitingDelay: number, recallDelay: number) => string = (waitingDelay: number, recallDelay: number) => `
+  onDisconnect: (target: string,
+                 message: () => string|undefined = () => `Connection closed for ${target}`,
+                 getErrorMessage: () => string = () => '',
+                 getHtml: (waitingDelay: number, recallDelay: number) => string = (waitingDelay: number, recallDelay: number) => `
       <p>
         Connection from [${os.hostname}] to ${target} was lost on ${moment().format('dd-MM-YYYY HH:mm:ss')}.
       </p>
@@ -131,18 +136,20 @@ export const mail = {
   `) => {
     return async (waitingDelay: number, recallDelay: number, cc?: string) => {
       console.log('Waiting %s seconds...', (waitingDelay / 1000).toFixed(0))
-      await queueEmail(`[dw] [${os.hostname}] ${message}`, getHtml(waitingDelay, recallDelay), cc)
+      await queueEmail(`[dw] [${os.hostname}] ${message()}`, getHtml(waitingDelay, recallDelay), cc)
     }
   },
 
-  onRestartSuccess: (target: string, message = `Connection recovered for ${target}`, getHtml: () => string = () => `
+  onRestartSuccess: (target: string,
+                     message: () => string|undefined = () => `Connection recovered for ${target}`,
+                     getHtml: () => string = () => `
       <p>
         Connection from [${os.hostname}] to ${target} was recovered on ${moment().format('dd-MM-YYYY HH:mm:ss')}.
       </p>
     `) => {
     return async (cc?: string) => {
-      console.log(`${message}`)
-      await queueEmail(`[dw] [${os.hostname}] ${message}`, getHtml(), cc)
+      console.log(`${message()}`)
+      await queueEmail(`[dw] [${os.hostname}] ${message()}`, getHtml(), cc)
     }
   },
 }
diff --git a/src/lib/watchers/abstract/url-watcher.ts b/src/lib/watchers/abstract/url-watcher.ts
index ea12d00..195d01a 100644
--- a/src/lib/watchers/abstract/url-watcher.ts
+++ b/src/lib/watchers/abstract/url-watcher.ts
@@ -47,7 +47,7 @@ export function urlWatcher(conf: Conf, checkValidity: (data: any) => Promise<Url
       conf.waitingDelay,
       conf.recallDelay,
 
-      mail.onEstablished(urlConf.address, getOkTitle()),
+      mail.onEstablished(urlConf.address, () => getOkTitle()),
 
       // When a disconnection is detected
         (waitingDelay: number, recallDelay, error?: any) => {
@@ -57,14 +57,14 @@ export function urlWatcher(conf: Conf, checkValidity: (data: any) => Promise<Url
           koTitle = getKoTitle()
           koMessage = () => `<p>${error.errorMessage}</p>`
         }
-        return mail.onDisconnect(urlConf.address, koTitle, koMessage)(waitingDelay, recallDelay)
+        return mail.onDisconnect(urlConf.address, () => koTitle, koMessage)(waitingDelay, recallDelay)
       },
 
       async () => {
         console.log('Trying to connect to %s', urlConf.address)
       },
 
-      mail.onRestartSuccess(urlConf.address, getRecoveredTitle()),
+      mail.onRestartSuccess(urlConf.address, () => getRecoveredTitle()),
     )
 
   }
diff --git a/src/lib/watchers/webdiff/webdiff-watcher.ts b/src/lib/watchers/webdiff/webdiff-watcher.ts
index 6e7d84b..6337cb5 100644
--- a/src/lib/watchers/webdiff/webdiff-watcher.ts
+++ b/src/lib/watchers/webdiff/webdiff-watcher.ts
@@ -61,10 +61,10 @@ export function webDiffWatcher(conf: Conf) {
       conf.waitingDelay,
       conf.recallDelay,
 
-      () => mail.onEstablished(target, 'webdiff successfully started')(webDiffConf.cc),
+      () => mail.onEstablished(target, () => 'webdiff successfully started')(webDiffConf.cc),
 
       // When a disconnection is detected
-      (waitingDelay: number, recallDelay: number) => mail.onDisconnect(target, 'Diff detected', undefined, (waitingDelay: number) => `
+      (waitingDelay: number, recallDelay: number) => mail.onDisconnect(target, () => 'Diff detected', undefined, (waitingDelay: number) => `
         ${htmlDiff}
         <p>
           Waiting ${(waitingDelay / 1000).toFixed(0)} seconds before trying to reconnect.
diff --git a/src/lib/watchers/ws2p/ws2p-watcher.ts b/src/lib/watchers/ws2p/ws2p-watcher.ts
index aa156cd..c3b4aca 100644
--- a/src/lib/watchers/ws2p/ws2p-watcher.ts
+++ b/src/lib/watchers/ws2p/ws2p-watcher.ts
@@ -44,16 +44,16 @@ export function ws2pWatcher(conf: Conf) {
       conf.waitingDelay,
       conf.recallDelay,
 
-      mail.onEstablished(target, `State OK WS2P on ${wserver.address}`),
+      mail.onEstablished(target, () => `State OK WS2P on ${wserver.address}`),
 
       // When a disconnection is detected
-      mail.onDisconnect(target, `State FAILURE WS2P on ${wserver.address}`),
+      mail.onDisconnect(target, () => `State FAILURE WS2P on ${wserver.address}`),
 
       async () => {
         console.log('Trying to connect to %s', target)
       },
 
-      mail.onRestartSuccess(target, `State RECOVERED WS2P on ${wserver.address}`),
+      mail.onRestartSuccess(target, () => `State RECOVERED WS2P on ${wserver.address}`),
     )
 
   }