Unable to send mail with attachment

I want to send mail with attachment to the customer, but its state always in InQueue(the attachment only 500kb)

PS:transfer mail without attachment is ok !

sever console

[07A4:0006-02EC] tell router sh

[03F4:0002-0CFC] Msgs State Via Destination

[03F4:0002-0CFC] 1 Busy(1) SMTP ***.COM (Push)

[03F4:0002-0CFC] 2 Retry( 2) SMTP [$Retry mx1.***.COM] (Push)

[03F4:0002-0CFC] Last error: Remote system no longer responding

[03F4:0002-0CFC] Next retry: 2013/11/26 15:10:31

[03F4:0002-0CFC] Transfer Threads: Max = 25; Total = 4; Inactive = 0; Max Concurrent = 12

[03F4:0002-0CFC] Delivery Threads: Max = 25; Total = 0; Inactive = 0

[03F4:0002-0CFC] Dispatch Threads: Max = 4; Total = 2; Inactive = 2

[03F4:0002-0CFC] Sweep Threads: Max = 4; Total = 2; Inactive = 2

thx a lot

Subject: Question

Did you try other file types?

Is this the only domain that is rejecting your email with the same attachment?

They might have filters on their side. You need to speak to the admin there to get it fixed

Subject: problerm remains

They said that they have a filter, need receive attachment with encrypted rar format, i did it but the problerm remains.

Subject: Work with them

find out what they are seeing and perhaps they can put you on a allow list and see what gets delivered to the user.