Some messages I attempted to publish were rejected due to an invalid signature.

The explorer shows no message content, but also no information about the message being rejected and the reason why. The only way to know that the message does not appear because it has been rejected is to access the /api/v0/messages/ API manually with the item_hash.

Example:

https://explorer.aleph.im/address/AVAX/X-1qzs9tdm4tt3e8k406eqp72mu5pe6ukejewpt4h/message/POST/c89caed08abcc3936cb14a8c8fae9f9832657e361da94c0c834ee959540f6cf4

https://api2.aleph.im/api/v0/messages/c89caed08abcc3936cb14a8c8fae9f9832657e361da94c0c834ee959540f6cf4