mail-auth VS smtp-server

Out of curiosity I was looking at the source code of a library that was posted here this week and I noticed that short strings are converted to u64 like this:

I have just released mail-auth, an e-mail authentication and reporting library written in Rust that supports the DKIM, ARC, SPF and DMARC protocols. It is the Rust equivalent of OpenDKIM, OpenSPF, OpenARC and OpenDMARC combined in one library (as well as some extras such ARF support) and includes the following features:

PEM issues for the TLS certificate or DKIM signature? In any case feel free to describe the problem in the discussions page and I'll check it out.

I am happy to announce Stalwart SMTP, a modern SMTP server developed in Rust with a focus on security, speed, and extensive configurability. It features built-in DMARC, DKIM, SPF and ARC support for message authentication, strong transport security through DANE, MTA-STS and SMTP TLS reporting, and offers great flexibility and customization thanks to its dynamic configuration rules and native support for Sieve scripts. The project has been recently awarded a grant from NLNet and the European Commission's Next Generation Internet program to develop a mail server in Rust. The next step in the roadmap is to refactor the code base of the previously released Stalwart JMAP/IMAP servers and to create an integrated mail server solution that is simple to install and manage. Any comments or suggestions are more than welcome!