diff --git a/mail/heirloom-mailx/Makefile b/mail/heirloom-mailx/Makefile
index 0bbf3ff46ac4..98d9e9eed479 100644
--- a/mail/heirloom-mailx/Makefile
+++ b/mail/heirloom-mailx/Makefile
@@ -1,46 +1,46 @@
 PORTNAME=	mailx
 PORTVERSION=	12.4
-PORTREVISION=	9
+PORTREVISION=	10
 CATEGORIES=	mail
 MASTER_SITES=	SF/heirloom/heirloom-${PORTNAME}/${PORTVERSION}
 PKGNAMEPREFIX=	heirloom-
 
 MAINTAINER=	cy@FreeBSD.org
 COMMENT=	BSD mail utility with MIME, IMAP, POP3, SMTP, and S/MIME extensions
 
 LICENSE=	BSD4CLAUSE
 
 OPTIONS_DEFINE=	IPV6 DOCS
 
 CONFLICTS=	mailx
 
 MAKE_JOBS_UNSAFE=	yes
 USES=		cpe iconv localbase ssl tar:bzip2
 CPE_VENDOR=	heirloom
 CPPFLAGS+=	-DOPENSSL_NO_SSL2
 MAKE_ARGS=	PREFIX="${PREFIX}" \
 		SYSCONFDIR="${PREFIX}/etc" \
 		SENDMAIL="/usr/sbin/sendmail" \
 		CPPFLAGS="${CPPFLAGS}" \
 		LDFLAGS="${LDFLAGS}"
 
 PORTDOCS=	AUTHORS COPYING ChangeLog README TODO
 
 .include <bsd.port.options.mk>
 
 .if ${PORT_OPTIONS:MIPV6}
 MAKE_ARGS+=	IPv6="-DHAVE_IPv6_FUNCS"
 .endif
 
 do-install:
 	${INSTALL_PROGRAM} ${WRKSRC}/${PORTNAME} ${STAGEDIR}${PREFIX}/bin
 	${INSTALL_MAN} ${WRKSRC}/${PORTNAME}.1 ${STAGEDIR}${MAN1PREFIX}/man/man1
 	${INSTALL_DATA} ${WRKSRC}/nail.rc ${STAGEDIR}${PREFIX}/etc/nail.rc.sample
 .if ${PORT_OPTIONS:MDOCS}
 	@${MKDIR} ${STAGEDIR}${DOCSDIR}
 .for i in ${PORTDOCS}
 	${INSTALL_DATA} ${WRKSRC}/${i} ${STAGEDIR}${DOCSDIR}
 .endfor
 .endif
 
 .include <bsd.port.mk>
diff --git a/mail/heirloom-mailx/files/patch-head.c b/mail/heirloom-mailx/files/patch-head.c
new file mode 100644
index 000000000000..546889ebe1bd
--- /dev/null
+++ b/mail/heirloom-mailx/files/patch-head.c
@@ -0,0 +1,14 @@
+--- head.c.orig	2006-03-03 16:01:19.000000000 -0800
++++ head.c	2022-01-26 18:13:57.270492000 -0800
+@@ -1116,10 +1116,8 @@
+ 	if ((t = combinetime(year, month, day, hour, minute, second)) ==
+ 			(time_t)-1)
+ 		goto invalid;
+-	tzdiff = t - mktime(gmtime(&t));
+ 	tmptr = localtime(&t);
+-	if (tmptr->tm_isdst > 0)
+-		tzdiff += 3600;
++	tzdiff = tmptr->tm_gmtoff; /* seconds east of GMT */
+ 	t -= tzdiff;
+ 	return t;
+ invalid:
diff --git a/mail/heirloom-mailx/files/patch-imap.c b/mail/heirloom-mailx/files/patch-imap.c
new file mode 100644
index 000000000000..b90d47a85384
--- /dev/null
+++ b/mail/heirloom-mailx/files/patch-imap.c
@@ -0,0 +1,30 @@
+--- imap.c.orig	2008-01-06 14:46:50.000000000 -0800
++++ imap.c	2022-01-26 18:13:57.271602000 -0800
+@@ -3506,10 +3506,8 @@
+ 		return -1;
+ 	if ((t = combinetime(year, month, day, 0, 0, 0)) == (time_t)-1)
+ 		return -1;
+-	tzdiff = t - mktime(gmtime(&t));
+ 	tmptr = localtime(&t);
+-	if (tmptr->tm_isdst > 0)
+-		tzdiff += 3600;
++	tzdiff = tmptr->tm_gmtoff; /* seconds east of GMT */
+ 	t -= tzdiff;
+ 	return t;
+ }
+@@ -3521,13 +3519,11 @@
+ 	struct tm	*tmptr;
+ 	int	tzdiff, tzdiff_hour, tzdiff_min;
+ 
+-	tzdiff = t - mktime(gmtime(&t));
++	tmptr = localtime(&t);
++	tzdiff = tmptr->tm_gmtoff; /* seconds east of GMT */
+ 	tzdiff_hour = (int)(tzdiff / 60);
+ 	tzdiff_min = tzdiff_hour % 60;
+ 	tzdiff_hour /= 60;
+-	tmptr = localtime(&t);
+-	if (tmptr->tm_isdst > 0)
+-		tzdiff_hour++;
+ 	snprintf(s, sizeof s, "\"%02d-%s-%04d %02d:%02d:%02d %+03d%02d\"",
+ 			tmptr->tm_mday,
+ 			month_names[tmptr->tm_mon],
diff --git a/mail/heirloom-mailx/files/patch-sendout.c b/mail/heirloom-mailx/files/patch-sendout.c
index d95e185c4e3a..77aa7195e2b6 100644
--- a/mail/heirloom-mailx/files/patch-sendout.c
+++ b/mail/heirloom-mailx/files/patch-sendout.c
@@ -1,10 +1,37 @@
---- sendout.c.orig	2022-01-26 14:24:22.000017000 -0800
-+++ sendout.c	2022-01-26 14:25:03.262517000 -0800
+--- sendout.c.orig	2008-07-03 23:09:57.000000000 -0700
++++ sendout.c	2022-01-26 18:25:05.091791000 -0800
 @@ -885,6 +885,7 @@
  				cp = expand(cp);
  			else
  				cp = SENDMAIL;
 +			args[0] = cp;
  			execv(cp, args);
  			perror(cp);
  		}
+@@ -1123,9 +1124,7 @@
+ 
+ /*
+  * Create a Date: header field.
+- * We compare the localtime() and gmtime() results to get the timezone,
+- * because numeric timezones are easier to read and because $TZ is
+- * not set on most GNU systems.
++ * We use tm->tm_gmtoff to account for negative DST adjustments (e.g. Ireland).
+  */
+ int
+ mkdate(FILE *fo, const char *field)
+@@ -1135,13 +1134,11 @@
+ 	int tzdiff, tzdiff_hour, tzdiff_min;
+ 
+ 	time(&t);
+-	tzdiff = t - mktime(gmtime(&t));
++	tmptr = localtime(&t);
++	tzdiff = tmptr->tm_gmtoff; /* seconds east of GMT */
+ 	tzdiff_hour = (int)(tzdiff / 60);
+ 	tzdiff_min = tzdiff_hour % 60;
+ 	tzdiff_hour /= 60;
+-	tmptr = localtime(&t);
+-	if (tmptr->tm_isdst > 0)
+-		tzdiff_hour++;
+ 	return fprintf(fo, "%s: %s, %02d %s %04d %02d:%02d:%02d %+05d\n",
+ 			field,
+ 			weekday_names[tmptr->tm_wday],