exception: use natural explanatory style

Author: dg

src/Mail/exceptions.php

@@ -13,28 +13,34 @@
 
 
 /**
- * Exception thrown when a mail sending error is encountered.
+ * Failed to send the email.
  */
 class SendException extends Nette\InvalidStateException
 {
 }
 
 
 /**
- * SMTP mailer exception.
+ * Failed to communicate with the SMTP server.
  */
 class SmtpException extends SendException
 {
 }
 
 
+/**
+ * All configured mailers failed to send the email.
+ */
 class FallbackMailerException extends SendException
 {
 	/** @var SendException[] */
 	public array $failures;
 }
 
 
+/**
+ * Failed to create or verify the email signature.
+ */
 class SignException extends SendException
 {
 }