[6.0] Deprecate unused phpmailer language string

[jgerman-bot]

New language relevant PR in upstream repo: joomla/joomla-cms#46294 Here are the upstream changes:

Click to expand the diff!

diff --git a/administrator/language/en-GB/joomla.ini b/administrator/language/en-GB/joomla.ini
index d91cba72dd62b..c9bef7933cf7e 100644
--- a/administrator/language/en-GB/joomla.ini
+++ b/administrator/language/en-GB/joomla.ini
@@ -926,6 +926,7 @@ PHPMAILER_RECIPIENTS_FAILED="SMTP Error! The following recipients failed: "
 PHPMAILER_SIGNING_ERROR="Signing error: "
 PHPMAILER_SMTP_CONNECT_FAILED="SMTP connect failed"
 PHPMAILER_SMTP_ERROR="SMTP server error: "
+; Deprecated, will be removed with 7.0
 PHPMAILER_TLS="Could not start TLS"
 PHPMAILER_VARIABLE_SET="Can't set or reset variable: "
 
diff --git a/api/language/en-GB/joomla.ini b/api/language/en-GB/joomla.ini
index a29ec02964bbb..70f4d506b1be4 100644
--- a/api/language/en-GB/joomla.ini
+++ b/api/language/en-GB/joomla.ini
@@ -915,6 +915,7 @@ PHPMAILER_RECIPIENTS_FAILED="SMTP Error! The following recipients failed: "
 PHPMAILER_SIGNING_ERROR="Signing error: "
 PHPMAILER_SMTP_CONNECT_FAILED="SMTP connect failed"
 PHPMAILER_SMTP_ERROR="SMTP server error: "
+; Deprecated, will be removed with 7.0
 PHPMAILER_TLS="Could not start TLS"
 PHPMAILER_VARIABLE_SET="Can't set or reset variable: "
 
diff --git a/language/en-GB/joomla.ini b/language/en-GB/joomla.ini
index 85d8332a4a0fe..4097cd8437ca1 100644
--- a/language/en-GB/joomla.ini
+++ b/language/en-GB/joomla.ini
@@ -495,6 +495,7 @@ PHPMAILER_RECIPIENTS_FAILED="SMTP Error! The following recipients failed: "
 PHPMAILER_SIGNING_ERROR="Signing error: "
 PHPMAILER_SMTP_CONNECT_FAILED="SMTP connect failed"
 PHPMAILER_SMTP_ERROR="SMTP server error: "
+; Deprecated, will be removed with 7.0
 PHPMAILER_TLS="Could not start TLS"
 PHPMAILER_VARIABLE_SET="Can't set or reset variable: "