The problem, of course, is that sendmail is figuring out the offset by comparing the hours and minutes shown by localtime() and gmtime().

That method should be reliable, so long as you pass the same timestamp to both localtime and gmtime. Can you give more details about the problem?

Do you have a routine that, given a time, returns the offset?

There's not one in the tz packages, but one is commonly included in GNU code. I'll enclose a copy at the end of this message. Of course the Right Way to do it is to use tm_gmtoff, but this isn't blessed by the standards.

/* Yield A - B, measured in seconds. */ time_t difftm (a, b) struct tm const *a; struct tm const *b; { : }

/* Yield the number of seconds that local time is ahead of GMT at time T, or 0 if this is not known. */ long gmtoff (t) time_t t; { : return difftm (ltp, &gmt); }

If you only need gmtoff() [and not the full generality of difftm()], a more simple solution that utilizes the fact that localtime() and gmtime() are never more than one day apart is ... long gmtoff(time_t t) { struct tm lcl = *localtime(&t); struct tm utc = *gmtime(&t); if (lcl.tm_mday != utc.tm_mday) (((lcl.tm_mon == utc.tm_mon) == (lcl.tm_mday > utc.tm_mday)) ? &lcl : &utc)->tm_hour += 24; return ((lcl.tm_hour - utc.tm_hour) * 60) + (lcl.tm_min - utc.tm_min); } Bradley