Acrobat Sign emails to recipient are bouncing before reaching recipient mail server

Hi everyone,

I'm experiencing an issue with Adobe Acrobat Sign where agreement notification emails to one recipient are repeatedly being marked as "bounced and could not be delivered."

The recipient's email address is valid and was receiving Acrobat Sign notifications normally until recently.

I have checked the recipient's email hosting environment with the hosting provider, and they have confirmed that:

• The mailbox is active and operational.
• There is sufficient mailbox storage available.
• The domain's MX records are correctly configured.
• Adobe Sign's sending address has been added to the email server's allow list.
• Other incoming emails are being received normally.
• Their mail-server logs show no incoming delivery attempt from Adobe at the times when Acrobat Sign reports the messages as bounced.
• They have therefore confirmed that the message is not being rejected by the recipient mailbox, quota, MX records, or their incoming mail system.

On the Acrobat Sign side, the agreement history shows:

• Email sent to the recipient → bounced
• Subsequent delivery attempts → bounced
• The same behaviour occurred across multiple attempts over two days.

Adobe Acrobat Sign's service status currently shows no ongoing outage affecting the service.

What I have already tried

1. Verified the recipient's email address.
2. Confirmed the mailbox is operational.
3. Confirmed sufficient mailbox storage.
4. Checked MX records.
5. Added Adobe Sign's sending address to the recipient's allow list.
6. Confirmed that other emails are reaching the mailbox.
7. Checked with the email hosting provider, which confirmed there is no corresponding incoming connection/delivery attempt in their mail logs.

What I would like to understand

Could this be related to an Adobe Acrobat Sign bounce/suppression mechanism or recipient-level delivery block?

If so:

• How can I determine whether the recipient is on a bounce/suppression list?
• Is there a way to clear/reset the recipient's delivery status?
• Can Acrobat Sign provide the actual SMTP response/bounce code associated with the failed delivery?
• Is there a way to obtain the Adobe message ID or sending-server information for the failed attempt?

I would appreciate any guidance from Adobe experts or anyone who has experienced a similar Acrobat Sign delivery issue.

AUDIT

Document e-signed by Mxxxxxxx(xxxxxxxx@gmail.com)

Signature Date: 2026-09-26 - 4:19:35 AM GMT - Time Source: server - Signature Appearance Selected: MOBILE_DRAW

Document emailed to yyyyyyyyyyy (xxxxxxx.com.au) for signature

2026-09-26 - 4:19:37 AM GMT

Email sent to yyyyyyyyyyyi (yyyyyyyyyyyy.com.au) bounced and could not be delivered

2026-09-26 - 4:19:42 AM GMT

Email sent to yyyyyyyyyyi (yyyyyyy.com.au) bounced and could not be delivered

2026-09-27 - 11:28:46 AM GMT

Email sent to yyyyyyyyi (yyyyyyyyy.com.au) bounced and could not be delivered

2026-09-27 - 11:38:06 AM GMT

Email sent to yyyyyyyyyyyyyy (yyyyyyyyyy.com.au) bounced and could not be delivered

2026-09-27 - 11:46:19 AM GMT