Forum OpenACS Development: Re: Error: can't rename to "_old_ns_sendmail": command already exists (Solved)
In general the policy of OpenACS to rename predefined commands is not great. In this case, the predefined sendmail mechanism of AOLServer or NaviServer (namely ns_sendmail) is essentially replaced by a send-mail implementation from the tcl library (presumably, since the the AOLserver variant was broken in some respects). However, at least the NaviServer variant has the advantage, that all of it's I/O never uses the select() system call and that it works therefore with file descriptors > 1000. Tcl I/O leads to crashes whenever a select() is called with high file descriptors (e.g. on async I/O, which is used often with timeouts, etc.).
There are so few calls to ns_sendmail in all packages such it seems much better to define (and use) an ad_sendmail, which calls then the favorite version ...
I solved that checking email configuration (I had a simple "localhost" insteead of "full qualified domain")
And I also had some problems (package requiere mime and package require base64) but it were solved installing tcllib (apt-get install tcllib in debian)
It's working fine now thanks!