Thank you for your feedback.

Unfortunately, we cannot reproduce the issue mentioned above.

Please send us an e-mail to mozdev@1und1.de. We are grateful to receive more details as follows:

1. MailCheck version
2. Firefox version
3. Error message (when exisiting)
4. Your e-mail provider

Providing screenshots or videos could be helpful to solve the problem quickly.

Best regards,

Your MailCheck team