我正在尝试使用Flutter中的mailer软件包发送带有附件的电子邮件，但是我的邮件在发生错误后发送。该错误是什么，我该如何解决？
我已在我的gmail帐户中打开了用于发送电子邮件的不太安全的访问权限。
这是我的代码：
final smtpServer = gmail('username', 'pass');
// Creating the Gmail server
final file = File(_filepath);
// Create our email message.
final message = Message()
..from = Address('username')
..recipients.add(_recipientController.text.trim()) //recipent email
..subject = _subjectController.text //subject of the email
..text = _bodyController.text
..attachments.add(FileAttachment(file)); //body of the email
try {
final sendReport = await send(message, smtpServer);
print('Message sent: ' + sendReport.toString());
_scaffoldKey.currentState.showSnackBar(SnackBar(
content: Text('Email Sent !'),
)); //print if the email is sent
} on SmtpMessageValidationException catch (e) {
print('Message sending error' + e.toString());
} on MailerException catch (e) {
print('Message not sent. \n' + e.toString());
for (var p in e.problems) {
print('Problem: ${p.code}: ${p.msg}');
}
}
。 。
这是我遇到的错误：
E/flutter (11764): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: Invalid message.
E/flutter (11764): #0 _validate (package:mailer/src/smtp/mail_sender.dart:118:5)
E/flutter (11764): #1 send (package:mailer/src/smtp/mail_sender.dart:92:3)
E/flutter (11764): #2 _SendEmailScreenState.sendDirectly (package:invoice_app/send_pdf_screen.dart:84:32)
E/flutter (11764): #3 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:779:19)
E/flutter (11764): #4 _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:862:36)
E/flutter (11764): #5 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24)
E/flutter (11764): #6 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:504:11)
E/flutter (11764): #7 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:282:5)
E/flutter (11764): #8 BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:217:7)
E/flutter (11764): #9 PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:475:9)
E/flutter (11764): #10 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:76:12)
E/flutter (11764): #11 PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:122:9)
E/flutter (11764): #12 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:379:8)
E/flutter (11764): #13 PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:120:18)
E/flutter (11764): #14 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:106:7)
E/flutter (11764): #15 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:218:19)
E/flutter (11764): #16 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:198:22)
E/flutter (11764): #17 GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:156:7)
E/flutter (11764): #18 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:102:7)
E/flutter (11764): #19 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:86:7)
E/flutter (11764): #20 _rootRunUnary (dart:async/zone.dart:1196:13)
E/flutter (11764): #21 _CustomZone.runUnary (dart:async/zone.dart:1085:19)
E/flutter (11764): #22 _CustomZone.runUnaryGuarded (dart:async/zone.dart:987:7)
E/flutter (11764): #23 _invoke1 (dart:ui/hooks.dart:275:10)
E/flutter (11764): #24 _dispatchPointerDataPacket (dart:ui/hooks.dart:184:5)
E/flutter (11764):