Email received from address will not send to

[Skysarge]

I get emails from individual regularly, and have been replying.
Now, I can get email from that address, but when I send I get "An error occurred while sending mail. The mail server responded: Syntax error in arguments. Please check the message recipient "..........."@gmail.com. and try again."
I used copy, reply, but still this message.
Anyone with ideas on what this is and why?

Sarge

[sach2]

Try creating a new mail to that address and see if it sends.

I did notice that in your error message there is a period(.) after gmail.com
not sure if that is a typo but an extra period in the address would give an error.

[Skysarge]

Saw what you mentioned. Sent test mail without period after gmail.com
No error message, and looks as though it went through.
Sarge

[pwillener]

Most likely the individual you received the original message from has his/her email account incorrectly set up, and sends out messages with an incorrect 'From:' address. So whenever you try to reply to that incorrect address, it will be returned as undeliverable.

[Skysarge]

I think that the incorrect return information or address is the cause. I removed the period after the word com, and sent an email. I have had no indication of problems. That was more than an hour ago, and in the past I have known almost right away the mai would not deliver.
I am going to consider this problem solved and closed unless something does pop up.
Thanks to all who submitted suggestions.
Sarge