As well as xoops running, I also have another private site for family tree. For both programs you can register and these are the results from both. The Family tree works without any garbled text. The xoops site is still garbled. I'm not sure if you can decipher the details and if it helps in any way
This is the info from the exim4 mainlog
Xoops register which sends emails but 'garbled'
2010-11-18 08:23:12 1PJ7GS-0001Fa-Km <=
andrew.xxx@yyy.ca U=nobody P=local S=685
2010-11-18 08:23:12 1PJ7GS-0001Fd-PK <=
andrew.xxx@yyy.ca U=nobody P=local S=1208
2010-11-18 08:23:13 1PJ7GS-0001Fa-Km =>
andrew.xxx@yyy.ca R=smarthost T=remote_smtp_smarthost H=yyymail.cg.yyycable.net [64.59.128.135]
2010-11-18 08:23:13 1PJ7GS-0001Fa-Km Completed
2010-11-18 08:23:13 1PJ7GS-0001Fd-PK =>
blobby@yyy1.ca R=smarthost T=remote_smtp_smarthost H=yyymail.cg.yyycable.net [24.71.223.43]
2010-11-18 08:23:13 1PJ7GS-0001Fd-PK Completed
Family tree register which sends emails and no problems
2010-11-18 08:27:45 1PJ7Kr-0001Ft-Sx <=
nobody@yyymail.no.yyycable.net U=nobody P=local S=1294
2010-11-18 08:27:46 1PJ7Ks-0001Fx-2B <=
nobody@yyymail.no.yyycable.net U=nobody P=local S=1288
2010-11-18 08:27:46 1PJ7Kr-0001Ft-Sx =>
norbut@yyy1.ca R=smarthost T=remote_smtp_smarthost H=yyymail.cg.yyycable.net [64.59.128.135]
2010-11-18 08:27:46 1PJ7Kr-0001Ft-Sx Completed
2010-11-18 08:27:46 1PJ7Ks-0001Fx-2B =>
andrew.xxx@yyy.ca R=smarthost T=remote_smtp_smarthost H=yyymail.cg.yyycable.net [64.59.128.135]
2010-11-18 08:27:46 1PJ7Ks-0001Fx-2B Completed